Update app.py

Add:
from huggingface_hub import hf_hub_download
from langchain_community.llms import LlamaCpp

app.py

@@ -16,6 +16,8 @@ from langchain_community.embeddings import HuggingFaceEmbeddings
 import torch
 
 from huggingface_hub import HfFolder
+from huggingface_hub import hf_hub_download
+from langchain_community.llms import LlamaCpp
 import gradio as gr
 
 from transformers import AutoTokenizer, AutoModelForCausalLM, pipeline, BitsAndBytesConfig