Change python-cryptography to python2-cryptography
    
    Package name is python2-cryptography and even that it Provides
    python-cryptography package, it causes problems during update of IPA
    on RHEL - python2-cryptography is not updated. After changing required package
    name to python2-cryptography upgrade on RHEL works well.
    
    Fixes: https://pagure.io/freeipa/issue/6749
    Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>