build(deps-dev): bump postcss from 8.4.14 to 8.4.31

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>

package.json

@@ -121,7 +121,7 @@
     "mobile-detect": "^1.4.5",
     "node-sass-tilde-importer": "^1.0.2",
     "package-lock-sanitizer": "^1.0.1",
-    "postcss": "^8.3.6",
+    "postcss": "^8.4.31",
     "postcss-cli": "^8.3.1",
     "prettier": "^2.3.2",
     "pretty-quick": "^3.1.1",