build(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-preview[bot] <support@dependabot.com>

package.json

@@ -22,7 +22,7 @@
     "chai-as-promised": "~7.1.1",
     "concurrently": "~6.0.0",
     "cross-env": "~7.0.0",
-    "eslint": "7.20.0",
+    "eslint": "7.21.0",
     "eslint-config-prettier": "7.2.0",
     "eslint-plugin-import": "2.22.1",
     "eslint-plugin-prettier": "3.3.1",