Update python-congressclient to rev 8 via SR 783827
    
    https://build.opensuse.org/request/show/783827
    by user dirkmueller + dimstar_suse
    - build against python 3.x only
    
    - update to version 1.13.0
      - Switch python3 versions of test jobs to match Train PTI
      - add releasenotes tox env and commands
      - Cap sphinx for py2 to match global requirements
      - OpenDev Migration Patch
      - Dropping the py35 testing
      - add python 3.7 unit test job
      - Changes for url transition to OpenDev