pylint: Ignore usage of 'unicode' before assignment

New versions of pylint ignore Python 2 functions and types, evaluating
'unicode' as "undefined". ansible-freeipa will always define 'unicode'
when running under Python 3, and it is always defined under Python 2.

This patch fixes these false positives.

plugins/modules/ipagroup.py

@@ -663,7 +663,9 @@ def main():
 
                 check_parameters(ansible_module, state, action)
 
-            elif isinstance(group_name, (str, unicode)):
+            elif (
+                isinstance(group_name, (str, unicode))  # pylint: disable=E0606
+            ):
                 name = group_name
             else:
                 ansible_module.fail_json(msg="Group '%s' is not valid" %