Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - xci: xci-lib.sh: Use the OSA requirements file for pip components

    OpenStack-Ansible maintains a requirements file which ensure that a
    working combination of pip/setuptools/wheels/virtualenv can be mixed up
    with distro packages so it's beneficial to take that into consideration
    when building our environment.

    Change-Id: Ic5398de3e464e1526f8d9fb6b6460907ac30084a
    Signed-off-by: Markos Chandras <mchandras@suse.de>