feat: upgrade linkinator from 4.1.2 to 6.1.0

Snyk has created this PR to upgrade linkinator from 4.1.2 to 6.1.0.

See this package in npm:
linkinator

See this project in Snyk:
https://app.snyk.io/org/cachiman/project/b5aaf3b1-fd61-4f9c-8762-3b007dfee39a?utm_source=github&utm_medium=referral&page=upgrade-pr

packages/google-cloud-aiplatform/package.json

@@ -66,7 +66,7 @@
     "jsdoc": "^4.0.0",
     "jsdoc-fresh": "^3.0.0",
     "jsdoc-region-tag": "^3.0.0",
-    "linkinator": "4.1.2",
+    "linkinator": "6.1.0",
     "long": "^5.2.3",
     "mocha": "^9.2.2",
     "pack-n-play": "^2.0.0",