Remove trailing backtick

 This patch is removing a trailing backtick (`) from the
doc/running-tests.rst document.

Change-Id: I66d555ad73738a1a7fb674a27472143e0f0d6609

doc/running-tests.rst

@@ -76,7 +76,7 @@ the ``kolla/tests/test_kolla_docker.py`` file:
     $ tox -e py27 test_kolla_docker.ModuleArgsTest
 
 To run the ``ModuleArgsTest.test_module_args`` test method in
-the ``kolla/tests/test_kolla_docker.py``` file:
+the ``kolla/tests/test_kolla_docker.py`` file:
 
 .. code-block:: console