Update app.py

app.py

@@ -212,7 +212,7 @@ def chatbot_fn(user_message, history):
     messages = system_messages + history + [{"role": "user", "content": user_message}]
 
     payload = {
-        "model": "gpt-4o",
+        "model": "gpt-4.5-preview",
         "messages": messages,
         "temperature": 0.2,
         "top_p": 1,