Update app.py

app.py

@@ -8,7 +8,7 @@ messages = [{"role": "system", "content": "You are an assistant"}]
 def CustomChatGPT(user_input):
     messages.append({"role": "user", "content": user_input})
     response = openai.ChatCompletion.create(
-        model = "gpt-4",
+        model = "gpt-3.5-turbo",
         messages = messages
     )
     ChatGPT_reply = response["choices"][0]["message"]["content"]