Update app.py

app.py

@@ -10,7 +10,7 @@ from langchain_huggingface import HuggingFaceEmbeddings
 from langchain_community.document_loaders import PyPDFLoader, TextLoader, Docx2txtLoader
 from langchain_text_splitters import RecursiveCharacterTextSplitter
 from langchain_community.retrievers import BM25Retriever
-from langchain.retrievers.ensemble import EnsembleRetriever
+from langchain_community.retrievers.ensemble import EnsembleRetriever
 from langchain.prompts import PromptTemplate
 
 # --- 1. SETUP API & SYSTEM PROMPT ---