Update app.py

app.py

@@ -1,7 +1,7 @@
 from langchain_community.embeddings import HuggingFaceBgeEmbeddings
 from langchain_community.document_loaders import PyPDFLoader, DirectoryLoader
 from langchain_community.vectorstores import Chroma
-from langchain.chains.retrieval_qa.base import RetrievalQA
+from langchain.chains import RetrievalQA
 from langchain_core.prompts import PromptTemplate
 from langchain.text_splitter import RecursiveCharacterTextSplitter
 from langchain_groq import ChatGroq