Update git submodules

* Update docs/submodules/releng from branch 'master'
  to d304c0a75d603d5d02e3a9c14d30baaefe980240
  - Install tox-pip-version too

    Change-Id: I93f61f14a4bdbf13bab08fdb355749fa3562e81c
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index ca696eb..d304c0a 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit ca696eb06520f8ad0eb97be450e0d7fd3685ed72
+Subproject commit d304c0a75d603d5d02e3a9c14d30baaefe980240