Update app.py

app.py

@@ -19,6 +19,8 @@ from langchain.document_loaders import (
 )
 from langchain.text_splitter import RecursiveCharacterTextSplitter
 from langchain.docstore.document import Document
+from sentence_transformers import SentenceTransformer
+from sentence_transformers.util import cos_sim
 from llama_cpp import Llama