Update app.py

changing import order of `os` package

app.py

@@ -1,3 +1,4 @@
+import os
 from langchain.embeddings.openai import OpenAIEmbeddings
 from langchain.document_loaders import PyMuPDFLoader
 from langchain.text_splitter import RecursiveCharacterTextSplitter
@@ -9,7 +10,7 @@ from langchain.prompts.chat import (
     SystemMessagePromptTemplate,
     HumanMessagePromptTemplate,
 )
-import os
+# import os
 import arxiv
 import chainlit as cl
 from chainlit import user_session