tests: Fix tests on macOS
tests: Fix tests on macOS

This also now tries to use only the appropriate headers/libs for the
given target Python version (though on Linux, at least, it seems like
it may not matter).

AbePralle/Rogue,AbePralle/Rogue,Plasmaworks/Rogue,Plasmaworks/Rogue,Plasmaworks/Rogue,Plasmaworks/Rogue