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

Author: renovate-bot

package.json

@@ -44,7 +44,7 @@
     "@types/extend": "^3.0.4",
     "@types/mocha": "^10.0.10",
     "@types/node": "^22.13.14",
-    "@types/sinon": "^17.0.4",
+    "@types/sinon": "^21.0.0",
     "@types/uuid": "^10.0.0",
     "c8": "^10.1.3",
     "gapic-tools": "^1.0.1",