add channel confirmation

ml/thing.py

@@ -450,6 +450,7 @@ def __on_broker_callback(self, ch, method, properties, body):
         elif isinstance(body, str):
             return
 
+        ch.basic_ack(method.delivery_tag)
         message_type = body.get("messageType")
         if message_type == "userMessage":
             self.on_user_message(body)