Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Change dir when calling stestr"
  - Change dir when calling stestr

    https://build.opnfv.org/ci/view/functest/job/functest-fuel-baremetal-daily-master/467/console

    Change-Id: Icaa773cf61397650e73a01b182a759dd64b11b95
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 1928ca2..18fdc04 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 1928ca2f26d9534378abac8619421ce3e4a032c2
+Subproject commit 18fdc04e02f4993259529a16edb30783760e59b0