Bump eslint from 6.8.0 to 9.21.0

Bumps [eslint](https://github.com/eslint/eslint) from 6.8.0 to 9.21.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/main/CHANGELOG.md)
- [Commits](eslint/eslint@v6.8.0...v9.21.0)

---
updated-dependencies:
- dependency-name: eslint
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package.json

@@ -33,7 +33,7 @@
   "homepage": "https://count.ly/",
   "dependencies": {},
   "devDependencies": {
-    "eslint": "^6.8.0",
+    "eslint": "^9.21.0",
     "eslint-config-airbnb-base": "^14.1.0",
     "eslint-plugin-import": "^2.20.1",
     "markdownlint": "^0.26.0",