Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "xci: install-lib: Make sure pip is upgraded first"
  - xci: install-lib: Make sure pip is upgraded first

    We need to make sure that pip is the first thing we upgrade in the
    virtual environment because old pip releases do not support the '-c'
    option which we use to install the rest of the required components.

    Change-Id: I8b3ec080617324bfefbec2a6cdfa6ef58afb7c20
    Signed-off-by: Markos Chandras <mchandras@suse.de>