Constrain wheel package versions
    
    The presence of IPA packages on PyPI revealed an interesting issue with
    make wheel_bundle. pip gives final releases a higher precedence than our
    development packages. make wheel_bundle downloads ipa 4.5.0 from PyPI
    instead of using our own wheels.
    
    Use a constraint file to enforce correct versions.
    
    https://pagure.io/freeipa/issue/6468
    
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Martin Basti <mbasti@redhat.com>