Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Allow overriding rally-tag if OpenStack master"
  - Allow overriding rally-tag if OpenStack master

    It allows setting a newer rally-openstack tag in ollivier containers
    to include "Fix the gates about cinder" [1].

    TypeError: create() got an unexpected keyword argument 'source_replica'

    [1] https://github.com/openstack/rally-openstack/commit/67882d55ca453d6aa863d279ec4cfc2b52c80f0a
    [2] https://bugs.launchpad.net/rally/+bug/1785519

    Change-Id: I5ed1002f345b0a9c51783850d09d0f336d0ed3d9
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 8714003..b2426d6 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 871400382c339114aedb529a5b6a7bbdd2067b46
+Subproject commit b2426d6614cbeeabe61d9258e42e7eca43bfde6e