build(deps-dev): bump postcss from 8.4.27 to 8.4.31 in /src/WebUI

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.27 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@8.4.27...8.4.31)

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

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

src/WebUI/package.json

@@ -60,7 +60,7 @@
     "jsdom": "^22.1.0",
     "json5": "^2.2.3",
     "mini-svg-data-uri": "^1.4.4",
-    "postcss": "^8.4.27",
+    "postcss": "^8.4.31",
     "prettier": "^3.0.1",
     "prettier-plugin-tailwindcss": "0.5.1",
     "rollup-plugin-visualizer": "^5.9.2",