Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 51a1b794c8abfb4468ee23cefa54b7474c359aea
  - Install dependencies before running tests

    Functest Kubernetes leverages agents in docker.

    Change-Id: I8ee44387b5193a4ba75e283b1465730a05082c5e
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 07d9f79..51a1b79 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 07d9f791bc93fa036041519689faa7292f560d56
+Subproject commit 51a1b794c8abfb4468ee23cefa54b7474c359aea