Update dependency @tryghost/validator to v3

Author: renovate[bot]

packages/mg-context/package.json

@@ -40,7 +40,7 @@
     "@tryghost/html-to-mobiledoc": "3.2.21",
     "@tryghost/kg-html-to-lexical": "1.2.38",
     "@tryghost/listr-smart-renderer": "workspace:*",
-    "@tryghost/validator": "2.0.3",
+    "@tryghost/validator": "3.1.0",
     "@typescript-eslint/parser": "8.59.0",
     "c8": "11.0.0",
     "eslint": "8.57.1",