chore(deps-dev): Bump @nextcloud/stylelint-config in /tests

Bumps [@nextcloud/stylelint-config](https://github.com/nextcloud/stylelint-config) from 2.3.1 to 2.4.0.
- [Release notes](https://github.com/nextcloud/stylelint-config/releases)
- [Changelog](https://github.com/nextcloud-libraries/stylelint-config/blob/master/CHANGELOG.md)
- [Commits](nextcloud-libraries/stylelint-config@v2.3.1...v2.4.0)

---
updated-dependencies:
- dependency-name: "@nextcloud/stylelint-config"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

tests/package.json

@@ -17,7 +17,7 @@
 		"@nextcloud/babel-config": "^1.0.0",
 		"@nextcloud/browserslist-config": "^3.0.0",
 		"@nextcloud/eslint-config": "^8.3.0",
-		"@nextcloud/stylelint-config": "^2.3.1"
+		"@nextcloud/stylelint-config": "^2.4.0"
 	},
 	"dependencies": {
 		"vue": "^2.7.16"