Update git submodules

* Update docs/submodules/releng from branch 'master'
  to f4bbcf4a338b163abdc08487ef8c8b6a87322ba4
  - Update Releng's tox.ini

    Change-Id: Id259757199bc8013d0d00d63194ba1e02e670a5a
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 49b4d79..f4bbcf4 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 49b4d799754af1993f067b646c4b64d02b67c53b
+Subproject commit f4bbcf4a338b163abdc08487ef8c8b6a87322ba4