Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Allow overriding the default OPENSTACK_TAG

    It allows building containers vs other upper-constraints and then
    reusing our Dockerfiles for an older or newer OpenStack versions.

    Change-Id: I160e6f7175a11684846cad86c3d47269c88a08ea
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index c254799..2845d29 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit c2547994a6b7dc0839f595f72a4f874a006a4638
+Subproject commit 2845d29b185043da58c434c218e5b409b5d23ac4