Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "don't print exceptions in atexit handler"
  - don't print exceptions in atexit handler

    atexit handler calls terminate_all after the regular python execution
    path, and it looks like the traceback stack is None somehow.

    In this context log.debug("", exc_info=True) doesn't work
    it prints out NoneType on Python3 and
    causes other problems on Python2.7

    remove the exc_info=True from the logging call

    JIRA: YARDSTICK-1107

    Change-Id: Ida0a0ced7ff5e017e2f8608880e3bb531724af95
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 0cfb413..f19016b 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 0cfb413451484e311ad5d3e956f3bb9c52f6978e
+Subproject commit f19016b39b828f648a66adc305cce17f5146e922