Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Update requests to 2.13.0 in virtualenvs

    It completes "Force requests===2.13.0" [1] which only updated all
    Docker files.

    [1] https://gerrit.opnfv.org/gerrit/#/c/45077/

    Change-Id: I416e01d86e82eb9e267a31463e75b6a4e11485c4
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 8797d07..516c249 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 8797d07d0be8309a1cdcc3c1c67b20ba064a4420
+Subproject commit 516c2497c84818b94de5dbef01683344e476dcfd