Bump @wordpress/stylelint-config from 20.0.2 to 21.3.0

Bumps [@wordpress/stylelint-config](https://github.com/WordPress/gutenberg/tree/HEAD/packages/stylelint-config) from 20.0.2 to 21.3.0.
- [Release notes](https://github.com/WordPress/gutenberg/releases)
- [Changelog](https://github.com/WordPress/gutenberg/blob/trunk/packages/stylelint-config/CHANGELOG.md)
- [Commits](https://github.com/WordPress/gutenberg/commits/@wordpress/stylelint-config@21.3.0/packages/stylelint-config)

---
updated-dependencies:
- dependency-name: "@wordpress/stylelint-config"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package-lock.json

@@ -20,7 +20,7 @@
   "devDependencies": {
     "@wordpress/env": "~5.2.0",
     "@wordpress/scripts": "~24.4.0",
-    "@wordpress/stylelint-config": "^20.0.2"
+    "@wordpress/stylelint-config": "^21.3.0"
   },
   "scripts": {
     "start": "wp-scripts start src/javascript/string-locator.js src/javascript/string-locator-search.js src/javascript/string-locator-replace.js",