Update app.py

app.py

@@ -3,7 +3,7 @@ import os
 import logging
 from langchain_core.prompts import ChatPromptTemplate
 from langchain_core.output_parsers import StrOutputParser
-#from langchain_openai import ChatOpenAI
+from langchain_nvidia_ai_endpoints import ChatNVIDIA
 from langchain_community.graphs import Neo4jGraph
 from typing import List, Tuple
 from pydantic import BaseModel, Field