Python 3 support
    
    Build a parallel installable python3-pyatspi package. The Fedora
    packaging guidelines require that both python2 and python3 modules are
    built from the same source rpm, so this is a bit hacky.
    
    With this change the "pyatspi" source package builds two binary rpms:
    "pyatspi"         - python2 support
    "python3-pyatspi" - python3 support
    
    It might make sense to rename the python2 package to "python-pyatspi" in
    the future to have a consistent naming with the python2 and python3
    subpackages.