Bump postcss from 8.4.38 to 8.5.3 in /frontend

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.38 to 8.5.3.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.38...8.5.3)

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

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

frontend/package.json

@@ -80,7 +80,7 @@
     "@xstate/inspect": "^0.8.0",
     "autoprefixer": "^10.4.20",
     "jest": "^29.7.0",
-    "postcss": "^8.4.35",
+    "postcss": "^8.5.3",
     "tailwindcss": "^3.3.5",
     "tailwindcss-blend-mode": "^1.0.0",
     "ts-jest": "^27.0.4",