Update app.py

app.py

@@ -7,6 +7,7 @@ from langchain.text_splitter import RecursiveCharacterTextSplitter
 from langchain.schema import Document
 from langchain.chains import RetrievalQA
 from langchain_core.retrievers import BaseRetriever
+from langchain_core.prompts import PromptTemplate
 from typing import List
 from pydantic import Field
 import numpy as np