Bump postcss from 8.4.19 to 8.4.31 in /js/ui (#74)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.19 to 8.4.31.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.4.19...8.4.31)

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

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js/ui/package.json

@@ -21,7 +21,7 @@
 		"https-browserify": "^1.0.0",
 		"mini-css-extract-plugin": "^2.4.5",
 		"os-browserify": "^0.3.0",
-		"postcss": "^8.2.8",
+		"postcss": "^8.4.31",
 		"postcss-load-config": "^3.0.1",
 		"postcss-loader": "^6.2.1",
 		"precss": "^4.0.0",