Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Bump oslo.messaging version to 5.36.0" into stable/fraser
  - Bump oslo.messaging version to 5.36.0

    A decoding error was introduced in the AMQP libraries installed by
    oslo.messaging version 5.30.2.

    Error example:

    File "/home/jenkins/opnfv/slave_root/workspace/yardstick-verify-master/
            .tox/functional/local/lib/python2.7/site-packages/amqp/utils.py",
             line 89, in str_to_bytes
      return s.encode('utf-8')
    UnicodeDecodeError: 'ascii' codec can't decode byte 0xd2 in position 3: ordinal not in range(128)

    This problem is fixed in the library versions installed in version 5.36.0.

    JIRA: YARDSTICK-1204

    Change-Id: I4719d8e0a0891ebbb3b87c31d593d15f897ef53a
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>
    (cherry-picked from commit bcc841699c8072a74378774593729931e81b4398)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index caeb546..6ad50ee 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit caeb546cd74b2727376b3da10c5fa86bd5209f8e
+Subproject commit 6ad50ee62571c9a860a728022a6c892b56fb0511