Update app.py

app.py

@@ -30,6 +30,7 @@ from langchain.embeddings import HuggingFaceInstructEmbeddings
 from langchain.embeddings import SentenceTransformerEmbeddings
 
 from langchain.document_loaders import SeleniumURLLoader, PyPDFLoader
+from langchain.docstore.document import Document
 
 from langchain.vectorstores import Chroma
 from langchain.text_splitter import RecursiveCharacterTextSplitter