build(deps-dev): bump postcss from 8.5.4 to 8.5.6

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.4 to 8.5.6.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.4...8.5.6)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

package-lock.json

@@ -34,7 +34,7 @@
     "autoprefixer": "^10.4.21",
     "markdownlint-cli": "^0.45.0",
     "markdownlint-cli2": "^0.18.1",
-    "postcss": "^8.5.4",
+    "postcss": "^8.5.6",
     "tailwindcss": "^4.1.8",
     "typescript": "5.8.3"
   }