Update app.py

app.py

@@ -1,4 +1,4 @@
-from gpt_index import SimpleDirectoryReader, GPTListIndex, GPTSimpleVectorIndex, LLMPredictor, PromptHelper, ServiceContext
+from llama_index import GPTVectorStoreIndex, SimpleDirectoryReader, LLMPredictor, ServiceContext, StorageContext, load_index_from_storage
 from langchain.chat_models import ChatOpenAI
 import gradio as gr
 import sys