Travis: archive logs of py3 jobs
    
    If something fails, only the logs of python2 jobs are currently
    collected. Collect python3 logs as well.
    
    Reviewed-By: Tibor Dudlak <tdudlak@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>