Update app.py

app.py

@@ -41,7 +41,7 @@ from langchain_community.document_loaders import TextLoader, PyPDFLoader
 from langchain_community.embeddings import HuggingFaceEmbeddings
 from langchain_community.llms import HuggingFaceHub
 #from langchain_community.chains import RetrievalQA
-from langchain.chains import RetrievalQA  # This one might still be in main langchain
+from langchain.chains.retrieval_qa.base import RetrievalQA   # This one might still be in main langchain
 from langchain_community.vectorstores import Chroma #from old library
 from langchain_groq import ChatGroq