Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 672d3a8a98de4cf22c35a5a84e73c6b079db6aea
  - Run tempest_cinder and tempest_keystone in hunter

    They have been backported for the best CNTT compliance.

    Change-Id: I8d8d19fc350af7804899ce91a58ca4b42b699c47
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 535c9ee..672d3a8 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 535c9eee14568beffb9832b01736e498b674d0b0
+Subproject commit 672d3a8a98de4cf22c35a5a84e73c6b079db6aea