build(deps-dev): bump eslint from 6.8.0 to 7.20.0 (#163)

Bumps [eslint](https://github.com/eslint/eslint) from 6.8.0 to 7.20.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v6.8.0...v7.20.0)

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