Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Update Functest gate jobs

    It conforms with the last updates of collivier.xtesting [1].

    [1] https://galaxy.ansible.com/collivier/xtesting

    Change-Id: Idd2c1599d161d558961fb5b3509c565593f7fc07
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index c11908f..3a5ccbb 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit c11908f4b14cd85eccfa02e4ff5810bb17dc4306
+Subproject commit 3a5ccbb6ea410517d013e269bb7aa9d28fdfb0cf