build(deps-dev): bump eslint in the eslint group across 1 directory

Bumps the eslint group with 1 update in the / directory: [eslint](https://github.com/eslint/eslint).


Updates `eslint` from 9.18.0 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@v9.18.0...v9.21.0)

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

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

package.json

@@ -38,7 +38,7 @@
   "devDependencies": {
     "@duckduckgo/eslint-config": "github:duckduckgo/eslint-config#v0.1.0",
     "@playwright/test": "^1.50.1",
-    "eslint": "^9.18.0",
+    "eslint": "^9.21.0",
     "minimist": "^1.2.8",
     "prettier": "3.4.2",
     "stylelint": "^15.11.0",