Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "jjb: xci: Run bifrost provisioning as normal user"
  - jjb: xci: Run bifrost provisioning as normal user

    Ansible can request elevated privileges using the 'become' directive.
    As such there is no need to run ansible using sudo. Furthermore,
    OpenStack CI runs all jobs as normal user and we need to do the same
    in order to compare behavior and results properly.

    Change-Id: Id198efd1d6fdf4619de931fbedc7caba8d68d2a0

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 5810ec4..78bbd36 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 5810ec4eaa3bddf165f255fd222f864712c5d34f
+Subproject commit 78bbd3674a26bfab52ad1dd780889101aa7021dc