new model

app.py

@@ -49,7 +49,8 @@ from langchain.retrievers import ContextualCompressionRetriever
 from langchain.retrievers.document_compressors import DocumentCompressorPipeline
 
 # --- Retrievers avanzados / reranker ---
-from langchain_community.retrievers import BM25Retriever, EnsembleRetriever
+from langchain_community.retrievers import BM25Retriever
+from langchain.retrievers import EnsembleRetriever
 from langchain.retrievers.multi_query import MultiQueryRetriever
 from langchain_community.cross_encoders import HuggingFaceCrossEncoder
 from langchain.retrievers.document_compressors import CrossEncoderReranker