fix walkthrough.ipynb render (#787)

recipes/use_cases/github_triage/walkthrough.ipynb

@@ -655,5 +655,7 @@
       "pygments_lexer": "ipython3",
       "version": "3.11.5"
     }
-  }
+  },
+  "nbformat": 4,
+  "nbformat_minor": 4
 }