change to mini

app.py

@@ -50,7 +50,7 @@ def predict(message, history, selected_option, username):
 
 
     response = client.chat.completions.create(
-         model='GPT-4o',
+         model='gpt-4o-mini',
     messages= history_openai_format,
     temperature=1,
     max_tokens=2000,