Modernize Python 2 code to get ready for Python 3

awx/main/queue.py

@@ -46,6 +46,6 @@ class CallbackQueueDispatcher(object):
                                  delivery_mode="persistent" if settings.PERSISTENT_CALLBACK_MESSAGES else "transient",
                                  routing_key=self.connection_queue)
                 return
-            except Exception, e:
+            except Exception as e:
                 self.logger.info('Publish Job Event Exception: %r, retry=%d', e,
                                  retry_count, exc_info=True)