Update topic_checking.py

remove if session.username when using anonymous client

hbmqtt/plugins/topic_checking.py

@@ -28,7 +28,7 @@ class TopicTabooPlugin(BaseTopicPlugin):
         if filter_result:
             session = kwargs.get('session', None)
             topic = kwargs.get('topic', None)
-            if session.username and topic:
+            if topic:
                 if session.username != 'admin' and topic in self._taboo:
                     return False
                 return True