Update app.py

app.py

@@ -9,7 +9,7 @@ from langchain_community.vectorstores import Chroma
 from langchain_community.document_loaders import UnstructuredPDFLoader, PyPDFLoader
 from langchain.text_splitter import CharacterTextSplitter
 from langchain.chains import RetrievalQAWithSourcesChain
-# from langchain.chains import load_qa_with_sources_from_chain_type
+from langchain.chains import load_qa_with_sources_from_chain_type
 from langchain.schema import Document
 from langchain.memory import ConversationBufferMemory
 from langchain.callbacks.manager import CallbackManager
@@ -77,7 +77,7 @@ def initialize_LLM(llm_option, llm_temperature, max_tokens, top_k, vector_db, pr
         print(f"Using default LLM {default_llm} for {language}")
         llm_name = default_llm
     
-    qa_chain = RetrievalQAWithSourcesChain(
+    qa_chain = load_qa_with_sources_from_chain_type(
         llm=llm_name,
         chain_type="stuff",
         retriever=vector_db.as_retriever(),