build(deps-dev): bump postcss in /website in the npm group

Bumps the npm group in /website with 1 update: [postcss](https://github.com/postcss/postcss).


Updates `postcss` from 8.5.3 to 8.5.4
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.3...8.5.4)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.4
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: npm
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

website/package-lock.json

@@ -5,7 +5,7 @@
     },
     "devDependencies": {
     "autoprefixer": "^10.4.21",
-    "postcss": "^8.5.3",
+    "postcss": "^8.5.6",
     "postcss-cli": "^11.0.1"
   }
 }