Make example work during pydantic transition (#11498)

**Description:**

Make the example extraction code on
https://python.langchain.com/docs/use_cases/extraction work again by
importing the langchain.pydantic_v1 lib instead of the v2.

**Issue:**

Solves issue https://github.com/langchain-ai/langchain/issues/11468

Co-authored-by: Martin van Hensbergen <martin@mvhensbergen.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

docs/docs/use_cases/extraction.ipynb

@@ -379,8 +379,8 @@
     }
    ],
    "source": [
-    "from typing import Optional, List\n",
-    "from pydantic import BaseModel, Field\n",
+    "from typing import Optional\n",
+    "from langchain.pydantic_v1 import BaseModel\n",
     "from langchain.chains import create_extraction_chain_pydantic\n",
     "\n",
     "# Pydantic data class\n",