load json from broker callback function

ml/thing.py

@@ -421,9 +421,8 @@ def __on_broker_callback(self, ch, method, properties, body):
         """
 
         if isinstance(body, bytes):
-            body_str = body.decode('utf8').replace("'", '"')
             try:
-                body = json.loads(body_str)
+                body = json.loads(body)
             except ValueError:
                 pass