chore(deps): update dependency @netlify/functions to v4

Author: renovate[bot]

package.json

@@ -28,7 +28,7 @@
     "openai": "^4.0.0"
   },
   "devDependencies": {
-    "@netlify/functions": "^3.1.10",
+    "@netlify/functions": "^4.2.4",
     "@types/node": "^22.0.0",
     "@typescript-eslint/eslint-plugin": "^6.0.0",
     "@typescript-eslint/parser": "^6.0.0",