docs: update pydantic comments -> callouts in tutorials (#1825)

docs/docs/tutorials/introduction.ipynb

@@ -2039,6 +2039,19 @@
     "Next, define a schema to show the model to let it decide to request assistance."
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "7bd3d704-5bee-4872-8d12-992bc970c158",
+   "metadata": {},
+   "source": [
+    "<div class=\"admonition note\">\n",
+    "    <p class=\"admonition-title\">Using Pydantic with LangChain</p>\n",
+    "    <p>\n",
+    "        This notebook uses Pydantic v2 <code>BaseModel</code>, which requires <code>langchain-core >= 0.3</code>. Using <code>langchain-core < 0.3</code> will result in errors due to mixing of Pydantic v1 and v2 <code>BaseModels</code>.\n",
+    "    </p>\n",
+    "</div>"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 21,
@@ -2046,7 +2059,6 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "# NOTE: you must use langchain-core >= 0.3 with Pydantic v2\n",
     "from pydantic import BaseModel\n",
     "\n",
     "class RequestAssistance(BaseModel):\n",