Bump postcss from 8.5.8 to 8.5.10 in /frontend

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.8 to 8.5.10.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.5.8...8.5.10)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.10
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

frontend/package.json

@@ -38,7 +38,7 @@
     "eslint-plugin-react": "^7.37.5",
     "eslint-plugin-react-hooks": "^7.0.1",
     "eslint-plugin-security": "^4.0.0",
-    "postcss": "^8.4.33",
+    "postcss": "^8.5.10",
     "tailwindcss": "^3.4.1",
     "typescript": "^5.9.3",
     "typescript-eslint": "^8.58.2",