Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "xci: Bump bifrost SHA"
  - xci: Bump bifrost SHA

    The latest bifrost code contains a fix when setting up DNS from a glean
    configuration drive and also a few virtualenv improvements. This allows
    us to get rid of all the workarounds we had in the past to switch
    Ansible versions in the middle of the XCI deployment.

    Change-Id: If49e290315ec96efdc07d04ff6624439c53aee19
    Signed-off-by: Markos Chandras <mchandras@suse.de>