chore(deps-dev): bump postcss in /examples/cms-cosmic

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.14 to 8.4.31.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.14...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
...

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

examples/cms-cosmic/package.json

@@ -21,7 +21,7 @@
     "@types/node": "^18.0.0",
     "@types/react": "^18.0.14",
     "autoprefixer": "10.4.7",
-    "postcss": "8.4.14",
+    "postcss": "8.4.31",
     "tailwindcss": "^3.1.4",
     "typescript": "^4.7.4"
   }