ci: fix notebook runner & VCR cassette recorder (#1849)

Co-authored-by: vbarda <vadym@langchain.dev>

docs/docs/tutorials/rag/langgraph_self_rag_local.ipynb

@@ -62,7 +62,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "%capture --no-stderr\n",
+    "%%capture --no-stderr\n",
     "%pip install -U langchain-nomic langchain_community tiktoken langchainhub chromadb langchain langgraph nomic[local]"
    ]
   },