Update app.py

app.py

@@ -200,7 +200,7 @@ async def on_chat_start():
     except Exception as e:
         heartbeat_task.cancel()
         await cl.Message(content=f"An error occurred: {str(e)}").send()
-        
+
 @cl.on_message
 async def main(message: cl.Message):
     index = cl.user_session.get("index")