Update app.py

app.py

@@ -3,6 +3,7 @@
 #https://github.com/ArjunAranetaCodes/Python-DataScience-AI/blob/main/Chain-LitChat-Mistral7b/app.py
 from langchain_openai import ChatOpenAI
 from langchain.chains import LLMChain
+from langchain_community.llms import HuggingFaceEndpoint
 from prompts import maths_assistant_prompt_template
 from langchain.memory.buffer import ConversationBufferMemory
 from dotenv import load_dotenv