chore(deps-dev): bump postcss in the dev-dependencies group (#366)

Bumps the dev-dependencies group with 1 update: [postcss](https://github.com/postcss/postcss).


Updates `postcss` from 8.5.20 to 8.5.21
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.20...8.5.21)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.21
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: dev-dependencies
...

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admin/package.json

@@ -22,7 +22,7 @@
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^6.0.3",
     "autoprefixer": "^10.5.4",
-    "postcss": "^8.5.20",
+    "postcss": "^8.5.21",
     "tailwindcss": "^4.3.3",
     "typescript": "^7.0.2",
     "vite": "^8.1.5"