Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Allow overriding default storage protocol

    It adds a new env var STORAGE_PROTOCOL to override storage_protocol
    in tempest. The default value is unchanged [1].

    [1] https://docs.openstack.org/tempest/latest/sampleconf.html

    Co-Authored-By: Viktor Tikkanen <viktor.tikkanen@nokia.com>
    Change-Id: I19e4e25212b6f6176e3b967e01eb634c15e4d474
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index ff2ba1f..a561c6c 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit ff2ba1fd18b05bf1b031e78d2589028968bbe906
+Subproject commit a561c6ca316feb1a203327aa729ac0317f70df48