Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Disable vnf testing in daily gates

    heat_ims sometimes fails.
    It mainly eases saving time when developping the workflow.

    Change-Id: I230461a3bae508bf60771df3f01a8271a2735065
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 2709b8a..fde3876 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 2709b8acc38cd1b1f6f847300f80730636223907
+Subproject commit fde38761ec1309f348c02693da938ea0e724e76a