build(deps-dev): bump postcss-nesting from 12.1.5 to 13.0.0 in /frontend

Bumps [postcss-nesting](https://github.com/csstools/postcss-plugins/tree/HEAD/plugins/postcss-nesting) from 12.1.5 to 13.0.0.
- [Changelog](https://github.com/csstools/postcss-plugins/blob/main/plugins/postcss-nesting/CHANGELOG.md)
- [Commits](https://github.com/csstools/postcss-plugins/commits/HEAD/plugins/postcss-nesting)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

frontend/package-lock.json

@@ -76,7 +76,7 @@
     "i18next-parser": "^9.0.1",
     "postcss": "^8.4.40",
     "postcss-modules": "^6.0.0",
-    "postcss-nesting": "^12.1.5",
+    "postcss-nesting": "^13.0.0",
     "prettier": "3.3.2",
     "react-test-renderer": "^18.3.1",
     "rimraf": "^6.0.1",