open-webui: patch imports for langchain v1

diff --git a/backend/open_webui/retrieval/utils.py b/backend/open_webui/retrieval/utils.py

index da570330b..6ea16e249 100644

--- a/backend/open_webui/retrieval/utils.py

+++ b/backend/open_webui/retrieval/utils.py

@@ -10,7 +10,7 @@ import re

 from urllib.parse import quote

 from huggingface_hub import snapshot_download

-from langchain.retrievers import ContextualCompressionRetriever, EnsembleRetriever

+from langchain_classic.retrievers import ContextualCompressionRetriever, EnsembleRetriever

 from langchain_community.retrievers import BM25Retriever

 from langchain_core.documents import Document

diff --git a/backend/open_webui/routers/retrieval.py b/backend/open_webui/routers/retrieval.py

index f8147372f..363bb4706 100644

--- a/backend/open_webui/routers/retrieval.py

+++ b/backend/open_webui/routers/retrieval.py

@@ -28,8 +28,7 @@ from pydantic import BaseModel

 import tiktoken

-from langchain.text_splitter import RecursiveCharacterTextSplitter, TokenTextSplitter

-from langchain_text_splitters import MarkdownHeaderTextSplitter

+from langchain_text_splitters import MarkdownHeaderTextSplitter, RecursiveCharacterTextSplitter, TokenTextSplitter

 from langchain_core.documents import Document

 from open_webui.models.files import FileModel, Files

  build-system = with python3Packages; [ hatchling ];

  patches = [ ./langchain-v1.patch ];

  # Not force-including the frontend build directory as frontend is managed by the `frontend` derivation above.

  postPatch = ''

    substituteInPlace pyproject.toml \

      iso-639

      itsdangerous

      langchain

      langchain-classic

      langchain-community

      langdetect

      ldap3