Fixes unit tests for vcmp guest module (#47792)

Tests were not working for ansible 2.8

lib/ansible/modules/network/f5/bigip_vcmp_guest.py

@@ -1,7 +1,7 @@
 #!/usr/bin/python
 # -*- coding: utf-8 -*-
 #
-# Copyright (c) 2017 F5 Networks Inc.
+# Copyright: (c) 2017, F5 Networks Inc.
 # GNU General Public License v3.0 (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
 
 from __future__ import absolute_import, division, print_function
@@ -462,7 +462,7 @@ class ModuleManager(object):
         if changed:
             self.changes = UsableChanges(params=changed)
 
-    def _update_changed_options(self):
+    def _update_changed_options(self):  # lgtm [py/similar-function]
         diff = Difference(self.want, self.have)
         updatables = Parameters.updatables
         changed = dict()