chore(deps-dev): bump eslint from 7.20.0 to 7.21.0

Bumps [eslint](https://github.com/eslint/eslint) from 7.20.0 to 7.21.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v7.20.0...v7.21.0)

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