ap: Constrain supported docutils
    
    New Sphinx 5.1.0 (Released: Jul 24, 2022) bumped supported docutils
    to 0.19:
    https://github.com/sphinx-doc/sphinx/pull/10656
    
    But m2r2 doesn't support it yet:
    https://github.com/CrossNox/m2r2/issues/52
    
    Thereby, docutils must be constrained to < 0.19.
    
    This should be fixed by m2r2 and after they do it the restriction
    can be removed.
    
    Fixes: https://pagure.io/freeipa/issue/9208
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>