Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "[Functest] Remove prepare_env from the docker cmds"
  - [Functest] Remove prepare_env from the docker cmds

    When [1] is merged, prepare_env won't exist and the call
    will fail. Keeps the former call until Euphrates jobs
    are stopped.

    [1] https://gerrit.opnfv.org/gerrit/#/c/47267/

    Change-Id: Ia41906f9e8ee15409cb28bb9bb621a7ab1964eee
    Signed-off-by: Jose Lausuch <jalausuch@suse.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index ffe2347..dca0a72 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit ffe23476fdee1f2dbb7ca810a25a96d64dc91be0
+Subproject commit dca0a72d315416f17dd4296299726b4fbcb88c8a