Bump stylelint from 16.20.0 to 16.21.0

Bumps [stylelint](https://github.com/stylelint/stylelint) from 16.20.0 to 16.21.0.
- [Release notes](https://github.com/stylelint/stylelint/releases)
- [Changelog](https://github.com/stylelint/stylelint/blob/main/CHANGELOG.md)
- [Commits](https://github.com/stylelint/stylelint/compare/16.20.0...16.21.0)

---
updated-dependencies:
- dependency-name: stylelint
  dependency-version: 16.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

package.json

@@ -4,7 +4,7 @@
     "csso-cli": "^4.0.2",
     "eslint": "^9.29.0",
     "html-minifier-terser": "^7.2.0",
-    "stylelint": "^16.20.0",
+    "stylelint": "^16.21.0",
     "stylelint-config-standard": "^38.0.0",
     "terser": "^5.43.1",
     "vnu-jar": "^24.10.17"