Update git submodules

* Update docs/submodules/functest from branch 'stable/euphrates'
  - Merge "Select ansible 2.3.2.0" into stable/euphrates
  - Select ansible 2.3.2.0

    Badly the ansible version is not defined in OpenStack's
    upper-constaints.txt. It must be added in the OPNFV one.

    Otherwise, rally fails [1]

    [1] https://build.opnfv.org/ci/job/functest-fuel-baremetal-daily-master/1866/console

    Change-Id: Id6814376ce96d35db65f6290d0a31283a15de0b2
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
    (cherry picked from commit c3c326570b29276d5ac2f703f64fb5f797de62d2)

diff --git a/docs/submodules/functest b/docs/submodules/functest
index cee4bd7..57b738e 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit cee4bd786b29987a3705c9e0178f73316e18fdc3
+Subproject commit 57b738ef5c47e790c1fe25aa6c1d876ced47f936