Removed deprecated is_authenticated() call

Author: Ross Mechanic

simple_history/models.py

@@ -286,7 +286,7 @@ def get_history_user(self, instance):
             return instance._history_user
         except AttributeError:
             try:
-                if self.thread.request.user.is_authenticated():
+                if self.thread.request.user.is_authenticated:
                     return self.thread.request.user
                 return None
             except AttributeError: