Update app.py

app.py

@@ -4,3 +4,6 @@ from langchain_community.document_loaders import PYPDFloader
 from langchain.txt_sliter import recursiveCharacterTextSpliter
 from langchain_community.vectorstores import chroma
 from langchain.chains import ConversationalRetrievalChain
+from langchain_community.embeddings import HuggingFaceEmbeddings
+from langchain_community.llmsimport uggingFacePipeline
+from langchain.chains import ConversationChain