build(deps-dev): bump eslint from 7.19.0 to 7.21.0

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] <support@github.com>

package.json

@@ -117,7 +117,7 @@
     "chai-spies": "^1.0.0",
     "dockerlint": "^0.3.9",
     "dotenv": "^8.2.0",
-    "eslint": "^7.19.0",
+    "eslint": "^7.21.0",
     "ioredis-mock": "^5.0.0",
     "markdownlint-cli": "^0.24.0",
     "mocha": "^8.1.3",