Bump eslint-config-stylelint from 20.0.0 to 21.0.0 (#160)

Bumps [eslint-config-stylelint](https://github.com/stylelint/eslint-config-stylelint) from 20.0.0 to 21.0.0.
- [Release notes](https://github.com/stylelint/eslint-config-stylelint/releases)
- [Changelog](https://github.com/stylelint/eslint-config-stylelint/blob/main/CHANGELOG.md)
- [Commits](stylelint/eslint-config-stylelint@20.0.0...21.0.0)

---
updated-dependencies:
- dependency-name: eslint-config-stylelint
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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