Bump postcss from 8.4.47 to 8.5.5

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.47 to 8.5.5.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.47...8.5.5)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.5
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

package-lock.json

@@ -47,7 +47,7 @@
     "netlify-cms-proxy-server": "^1.3.23",
     "npm-run-all": "^4.1.5",
     "pa11y-ci": "^3.1.0",
-    "postcss": "^8.4.47",
+    "postcss": "^8.5.5",
     "postcss-cli": "^9.1.0",
     "prettier": "3.3.3",
     "rimraf": "^3.0.2",