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>

Author: dependabot-preview[bot]

package-lock.json

@@ -21,7 +21,7 @@
     "@types/ws": "^7.4.0",
     "@typescript-eslint/eslint-plugin": "^2.34.0",
     "@typescript-eslint/parser": "^2.34.0",
-    "eslint": "^7.20.0",
+    "eslint": "^7.21.0",
     "ts-node": "^9.1.1",
     "typescript": "^4.2.2"
   },