chore(deps): update dependency @types/sinon to v21

Author: renovate[bot]

testing/util/package-lock.json

@@ -21,7 +21,7 @@
     "@types/mocha": "^10.0.7",
     "@types/mock-fs": "^4.13.4",
     "@types/node": "^22.0.0",
-    "@types/sinon": "^17.0.3",
+    "@types/sinon": "^21.0.0",
     "@types/unist": "^3.0.2",
     "@types/yargs": "^17.0.32",
     "mock-fs": "^5.1.4",