chore(deps-dev): bump @cloudflare/workers-types in /workers

Bumps [@cloudflare/workers-types](https://github.com/cloudflare/workerd) from 4.20250918.0 to 4.20250921.0.
- [Release notes](https://github.com/cloudflare/workerd/releases)
- [Changelog](https://github.com/cloudflare/workerd/blob/main/Dockerfile.release)
- [Commits](https://github.com/cloudflare/workerd/commits)

---
updated-dependencies:
- dependency-name: "@cloudflare/workers-types"
  dependency-version: 4.20250921.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

workers/package-lock.json

@@ -32,7 +32,7 @@
     "hono": "^4.0.0"
   },
   "devDependencies": {
-    "@cloudflare/workers-types": "^4.0.0",
+    "@cloudflare/workers-types": "^4.20250921.0",
     "@vitest/ui": "^1.0.0",
     "eslint": "^8.0.0",
     "prettier": "^3.0.0",