Bump postcss from 8.4.23 to 8.4.31 in /templates/default

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.23 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@8.4.23...8.4.31)

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

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

templates/default/package.json

@@ -43,7 +43,7 @@
 		"jest": "^29.5.0",
 		"jest-environment-jsdom": "^29.5.0",
 		"mini-css-extract-plugin": "^2.7.6",
-		"postcss": "^8.4.23",
+		"postcss": "^8.4.31",
 		"postcss-loader": "^7.3.0",
 		"postcss-nested": "^6.0.1",
 		"postcss-preset-env": "^8.4.1",