Removes tuple unpacking from memcache test

Per pep 3113 Python 3 does not support tuple parameter
unpacking. This change removes the tuple from the function
param in the memcache plugin test since nothing is done
with it anyway.

Change-Id: I08c84cab308bbb405e5864fb0417f00c5310e71a
Closes-Bug: 1689347
Signed-off-by: Michael Rice <michael@michaelrice.org>

tests/test_plugin_memcache.py

@@ -56,7 +56,7 @@ class TestMemcache(object):
 
     def test_get_memcached_stats(self, monkeypatch):
         """Ensure that get_memcached_stats() works."""
-        def mock_memcache_client(cls, (conn_tuple)):
+        def mock_memcache_client(cls, conn_tuple):
             """Mock a memcache client class."""
             return None