Update app.py

app.py

@@ -3,7 +3,7 @@ from langchain_community.document_loaders import WebBaseLoader
 from langchain.text_splitter import RecursiveCharacterTextSplitter
 from langchain.vectorstores import Chroma
 from langchain.embeddings import OpenAIEmbeddings
-from langchain.chat_models import ChatOpenAI
+from langchain_openai import ChatOpenAI
 from langchain import hub
 from langchain.schema.runnable import RunnablePassthrough
 from langchain.schema.output_parser import StrOutputParser