chore(deps-dev): bump postcss (#6173)

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


Updates `postcss` from 8.5.21 to 8.5.23
- [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/8.5.21...8.5.23)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.23
  dependency-type: direct:development
  dependency-group: npm_and_yarn
...

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docs/package.json

@@ -42,7 +42,7 @@
     "@types/react-dom": "^19.2.3",
     "eslint": "^9.39.5",
     "eslint-config-next": "16.2.11",
-    "postcss": "^8.5.21",
+    "postcss": "^8.5.23",
     "prettier": "^3.9.6",
     "tailwindcss": "^4.3.3",
     "typescript": "^6.0.3",