Update app.py

Updated model to 4.1 nano

app.py

@@ -16,7 +16,7 @@ if __name__ == "__main__":
     try:
         # Instantiate the ChatbotInterface class and create the interface
         chatbot_interface = ChatbotInterface(
-            model="gpt-4o-mini",
+            model="gpt-4.1-nano",
             temperature=0,
             max_output_tokens=600,
             max_num_results=5