docs: keep tutorial runnable in CI (#30556)

Author: ccurme

docs/docs/tutorials/llm_chain.ipynb

@@ -90,16 +90,9 @@
     "export LANGSMITH_PROJECT=\"default\" # or any other project name\n",
     "```\n",
     "\n",
-    "Or, if in a notebook, you can set them with:"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 4,
-   "id": "599bb688",
-   "metadata": {},
-   "outputs": [],
-   "source": [
+    "Or, if in a notebook, you can set them with:\n",
+    "\n",
+    "```python\n",
     "import getpass\n",
     "import os\n",
     "\n",
@@ -125,7 +118,8 @@
     "if \"OPENAI_API_KEY\" not in os.environ:\n",
     "    os.environ[\"OPENAI_API_KEY\"] = getpass.getpass(\n",
     "        prompt=\"Enter your OpenAI API key (required if using OpenAI): \"\n",
-    "    )"
+    "    )\n",
+    "```"
    ]
   },
   {