Bump eslint from 7.20.0 to 7.21.0 (#5179)

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)

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

package.json

@@ -184,7 +184,7 @@
     "benchmark": "^2.1.4",
     "common-tags": "^1.8.0",
     "del": "^6.0.0",
-    "eslint": "^7.20.0",
+    "eslint": "^7.21.0",
     "eslint-config-stylelint": "^13.1.0",
     "got": "^11.8.2",
     "husky": "^5.1.2",