chore(deps-dev): bump postcss from 8.4.12 to 8.4.31 in /src/main/webapp

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.12 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@8.4.12...8.4.31)

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

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

src/main/webapp/package.json

@@ -107,7 +107,7 @@
     "less": "4.1.2",
     "less-loader": "10.2.0",
     "mini-css-extract-plugin": "2.6.0",
-    "postcss": "8.4.12",
+    "postcss": "8.4.31",
     "postcss-import": "14.1.0",
     "postcss-loader": "6.2.1",
     "postcss-preset-env": "7.4.3",