chore(deps-dev): bump eslint from 7.19.0 to 7.21.0 (microsoft#67)

Bumps [eslint](https://github.com/eslint/eslint) from 7.19.0 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@v7.19.0...v7.21.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]