Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "xci: install: Move all pip installations to virtualenv"
  - xci: install: Move all pip installations to virtualenv

    Now that all pip installations are managed in the same way we can
    move them inside a global virtual environment to further isolate the
    XCI artifacts from the rest of the system. Moreover, we further simplify
    the initial package installation to install everything at once instead
    of calling the package manager for every single package that we need.

    Change-Id: I6a170d2439fae8b0653f3141e0e8bb8ead67657e
    Signed-off-by: Markos Chandras <mchandras@suse.de>