add heart beat

app.py

@@ -1502,9 +1502,9 @@ def Text2Sound_HMI():
     #     return None
 
 def UpdateChatbot(Running_history):
-    # timestr = time.strftime("%Y%m%d-%H%M%S")
-    # Running_history = Running_history + [(None, timestr)]
-    return Running_history
+    timestr = time.strftime("%Y%m%d-%H%M%S")
+    Running_history = Running_history + [(None, timestr)]
+    yield Running_history
 
 global last_answer
 last_answer = ""