Update git submodules

* Update docs/submodules/functest from branch 'stable/euphrates'
  - Add post_push hooks

    It allows creating the stable tags as allowed by Docker hub [1].

    [1] https://github.com/docker/hub-feedback/issues/341

    Change-Id: I84909b20fc8b926eb5414db7d57100aaa6060f84
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 0b15334..4108e6a 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 0b15334d7f241d4da822d7c843fd2dfc5d1fdbac
+Subproject commit 4108e6a707b39872be8714d6e54984a93f920413