fix: replace openai import

app.py

@@ -5,7 +5,7 @@ import sqlalchemy
 import sqlite_vss
 import streamlit as st
 import streamlit.components.v1 as components
-from langchain import OpenAI
+from langchain.llms import OpenAI
 from langchain.callbacks import get_openai_callback
 from langchain.chains import ConversationalRetrievalChain
 from langchain.chains.conversation.memory import ConversationBufferMemory