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

@@ -99,7 +99,7 @@
     "lint-staged": "16.1.2",
     "npm-check-updates": "18.0.1",
     "plop": "3.1.2",
-    "postcss": "8.5.4",
+    "postcss": "8.5.6",
     "postcss-advanced-variables": "5.0.0",
     "postcss-cli": "11.0.1",
     "postcss-custom-properties": "14.0.5",