python3: port certmonger requests script
    
    This commit fixes requesting certificates via certmonger in Python 3.
    This includes dogtag-ipa-ca-renew-agent-submit script and scripts
    used during the scripts restarting.
    
    https://pagure.io/freeipa/issue/4985
    
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>