This PR is a follow up of bitcoin/bitcoin#23489, and it updates Qt version in docs and CI.
Qt configure summary on Windows 10 Pro 21H1 (build 19043.1348):
  0Configure summary:
  1
  2Build type: win32-msvc (x86_64, CPU features: sse sse2)
  3Compiler: msvc 192829913
  4Configuration: sse2 aesni sse3 ssse3 sse4_1 sse4_2 avx avx2 avx512f avx512bw avx512cd avx512dq avx512er avx512ifma avx512pf avx512vbmi avx512vl compile_examples f16c largefile msvc_mp precompile_header rdrnd rdseed shani silent x86SimdAlways release c++11 c++14 c++17 c++1z concurrent no-pkg-config static static_runtime stl
  5Build options:
  6  Mode ................................... release
  7  Optimize release build for size ........ no
  8  Building shared libraries .............. no
  9  Using C standard ....................... C89
 10  Using C++ standard ..................... C++17
 11  Relocatable ............................ no
 12  Using precompiled headers .............. yes
 13  Using LTCG ............................. no
 14  Target compiler supports:
 15    SSE .................................. SSE2 SSE3 SSSE3 SSE4.1 SSE4.2
 16    AVX .................................. AVX AVX2
 17    AVX512 ............................... F ER CD PF DQ BW VL IFMA VBMI
 18    Other x86 ............................ AES F16C RDRAND SHA
 19  Build parts ............................ libs
 20  App store compliance ................... no
 21Qt modules and options:
 22  Qt Concurrent .......................... yes
 23  Qt D-Bus ............................... no
 24  Qt D-Bus directly linked to libdbus .... no
 25  Qt Gui ................................. yes
 26  Qt Network ............................. yes
 27  Qt Sql ................................. no
 28  Qt Testlib ............................. yes
 29  Qt Widgets ............................. yes
 30  Qt Xml ................................. no
 31Support enabled for:
 32  Using pkg-config ....................... no
 33  udev ................................... no
 34  Using system zlib ...................... no
 35  Zstandard support ...................... no
 36Qt Core:
 37  DoubleConversion ....................... yes
 38    Using system DoubleConversion ........ no
 39  GLib ................................... no
 40  iconv .................................. no
 41  ICU .................................... no
 42  Built-in copy of the MIME database ..... yes
 43  Tracing backend ........................ <none>
 44  Logging backends:
 45    journald ............................. no
 46    syslog ............................... no
 47    slog2 ................................ no
 48  PCRE2 .................................. yes
 49    Using system PCRE2 ................... no
 50Qt Network:
 51  getifaddrs() ........................... no
 52  IPv6 ifname ............................ no
 53  libproxy ............................... no
 54  Schannel ............................... no
 55  OpenSSL ................................ no
 56    Qt directly linked to OpenSSL ........ no
 57  OpenSSL 1.1 ............................ no
 58  DTLS ................................... no
 59  OCSP-stapling .......................... no
 60  SCTP ................................... no
 61  Use system proxies ..................... yes
 62  GSSAPI ................................. no
 63Qt Gui:
 64  Accessibility .......................... yes
 65  FreeType ............................... yes
 66    Using system FreeType ................ no
 67  HarfBuzz ............................... yes
 68    Using system HarfBuzz ................ no
 69  Fontconfig ............................. no
 70  Image formats:
 71    GIF .................................. no
 72    ICO .................................. no
 73    JPEG ................................. no
 74      Using system libjpeg ............... no
 75    PNG .................................. yes
 76      Using system libpng ................ no
 77  Text formats:
 78    HtmlParser ........................... yes
 79    CssParser ............................ yes
 80    OdfWriter ............................ no
 81    MarkdownReader ....................... yes
 82      Using system libmd4c ............... no
 83    MarkdownWriter ....................... no
 84  EGL .................................... no
 85  OpenVG ................................. no
 86  OpenGL:
 87    ANGLE ................................ no
 88    Desktop OpenGL ....................... yes
 89    Dynamic OpenGL ....................... no
 90    OpenGL ES 2.0 ........................ no
 91    OpenGL ES 3.0 ........................ no
 92    OpenGL ES 3.1 ........................ no
 93    OpenGL ES 3.2 ........................ no
 94  Vulkan ................................. no
 95  Session Management ..................... yes
 96Features used by QPA backends:
 97  evdev .................................. no
 98  libinput ............................... no
 99  INTEGRITY HID .......................... no
100  mtdev .................................. no
101  tslib .................................. no
102  xkbcommon .............................. no
103  X11 specific:
104    XLib ................................. no
105    XCB Xlib ............................. no
106    EGL on X11 ........................... no
107    xkbcommon-x11 ........................ no
108QPA backends:
109  DirectFB ............................... no
110  EGLFS .................................. no
111  LinuxFB ................................ no
112  VNC .................................... no
113  Windows:
114    Direct 2D ............................ yes
115    DirectWrite .......................... yes
116    DirectWrite 2 ........................ yes
117Qt Sql:
118  SQL item models ........................ no
119Qt Widgets:
120  GTK+ ................................... no
121  Styles ................................. Fusion Windows WindowsVista
122Qt PrintSupport:
123  CUPS ................................... no
124Qt Sql Drivers:
125  DB2 (IBM) .............................. no
126  InterBase .............................. no
127  MySql .................................. no
128  OCI (Oracle) ........................... no
129  ODBC ................................... no
130  PostgreSQL ............................. no
131  SQLite2 ................................ no
132  SQLite ................................. no
133    Using system provided SQLite ......... no
134  TDS (Sybase) ........................... no
135Qt Testlib:
136  Tester for item models ................. yes
137Qt Tools:
138  Qt Assistant ........................... yes
139  Qt Designer ............................ yes
140  Qt Distance Field Generator ............ yes
141  kmap2qmap .............................. yes
142  Qt Linguist ............................ yes
143  Mac Deployment Tool .................... no
144  makeqpf ................................ yes
145  pixeltool .............................. yes
146  qdbus .................................. yes
147  qev .................................... yes
148  Qt Attributions Scanner ................ yes
149  qtdiag ................................. yes
150  qtpaths ................................ yes
151  qtplugininfo ........................... yes
152  Windows deployment tool ................ yes
153  WinRT Runner Tool ...................... no
154Qt Tools:
155  QDoc ................................... no
156
157Note: Using static linking will disable the use of dynamically
158loaded plugins. Make sure to import all needed static plugins,
159or compile needed modules into the library.