Update app.py

app.py

@@ -11,7 +11,7 @@ def chat(input):
     user_message = f'<span class="user">您说：{input}</span><br>'
     response = requests.post(url, json=data, headers=headers)
     bot_message = f'<span class="chatbot">ChatGPT：{response.text}</span><br>'
-    conversation_history += user_message + bot_message
+    conversation_history = user_message + bot_message
     return conversation_history
 
 css = '''