Fixing the GPT model reference

app.py

@@ -22,9 +22,9 @@ Think through your response step by step.
 @cl.on_chat_start  # marks a function that will be executed at the start of a user session
 async def start_chat():
     settings = {
-        "model": "gpt-3.5-turbo",
+        "model": "gpt-4-1106-preview",
         "temperature": 0,
-        "max_tokens": 500,
+        "max_tokens": 4000,
         "top_p": 1,
         "frequency_penalty": 0,
         "presence_penalty": 0,