Bump @wordpress/eslint-plugin from 22.20.0 to 22.21.0

Bumps [@wordpress/eslint-plugin](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin) from 22.20.0 to 22.21.0.
- [Release notes](https://github.com/WordPress/gutenberg/releases)
- [Changelog](https://github.com/WordPress/gutenberg/blob/trunk/packages/eslint-plugin/CHANGELOG.md)
- [Commits](https://github.com/WordPress/gutenberg/commits/@wordpress/[email protected]/packages/eslint-plugin)

---
updated-dependencies:
- dependency-name: "@wordpress/eslint-plugin"
  dependency-version: 22.21.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]