Support Unit Tests on Windows and MSYS2/MinGW64

[Paebbels]

Unit tests are currently not possible on Windows and MSYS2/MinGW64 due to missing features in pyTooling/Actions → UnitTest and Coverage job templates.

See also:

• Support environment variables for UnitTest and Coverage pyTooling/Actions#44
• Support custom (pre-)commands for UnitTest and Coverage pyTooling/Actions#45