updated the code to replace the old-style string formatting with f-strings for better readability and consistency. For example, this:
0raise ValueError('aux_rand must be 32 bytes instead of %i.' % len(aux_rand))
has been changed to:
0raise ValueError(f'aux_rand must be 32 bytes instead of {len(aux_rand)}.')
Similarly, all instances of old-style formatting, such as:
0print(' * Signing test raised exception:', e)
have been updated to:
0print(f' * Signing test raised exception: {e}')