Bump postcss from 8.4.21 to 8.4.31

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.21 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@8.4.21...8.4.31)

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

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

package.json

@@ -37,7 +37,7 @@
     "@typescript-eslint/parser": "5.51.0",
     "css-loader": "5.2.7",
     "eslint": "8.33.0",
-    "postcss": "8.4.21",
+    "postcss": "8.4.31",
     "postcss-loader": "7.0.2",
     "rxjs": "7.5.6",
     "style-loader": "3.3.1",