Update app.py

app.py

@@ -1,6 +1,6 @@
 import streamlit as st
 from streamlit_chat import message
-from langchain_community.chains import ConversationalRetrievalChain
+from langchain.chains import ConversationalRetrievalChain
 from langchain_community.document_loaders import PyPDFLoader, DirectoryLoader
 from langchain_community.embeddings import HuggingFaceEmbeddings
 from langchain_community.llms import CTransformers