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

@@ -88,7 +88,7 @@
     "chai-string": "^1.5.0",
     "chokidar-cli": "^2.1.0",
     "cross-env": "^7.0.3",
-    "eslint": "^7.19.0",
+    "eslint": "^7.21.0",
     "eslint-config-raine": "^0.2.2",
     "eslint-config-standard": "^16.0.2",
     "eslint-plugin-fp": "^2.3.0",