chore(deps): update dependency sinon to v21

Author: renovate[bot]

package.json

@@ -30,7 +30,7 @@
     "@cloudflare/workers-types": "^4.20250121.0",
     "@types/chai": "^5.0.1",
     "@types/mocha": "^10.0.10",
-    "@types/sinon": "^17.0.3",
+    "@types/sinon": "^21.0.0",
     "c8": "^10.1.3",
     "chai": "^5.1.2",
     "dotenv": "^16.4.7",
@@ -40,7 +40,7 @@
     "mocha": "^11.1.0",
     "pnpm": "^10.2.0",
     "prettier": "^3.4.2",
-    "sinon": "^19.0.2",
+    "sinon": "^21.0.0",
     "typescript": "^5.7.3",
     "wrangler": "^3.107.2"
   }