Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Remove Python packaging files"
  - Remove Python packaging files

    Since we don't release releng as a python project, it doesn't make much
    sense to include a setup.py.

    The jjb testenv in tox.ini is modified to pin jenkins-job-builder and no
    longer require setup.py nor jjb/test-requirements.txt, and the modules
    testenv is moved to it's own tox.ini under modules.

    Locally testing of jjb can still be done using:

      tox -e jjb

    Change-Id: I512b1a8f9cd7d48a2f14b1bbe966b525793a6fe3
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>