Bump postcss from 8.4.23 to 8.4.31

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](https://github.com/postcss/postcss/compare/8.4.23...8.4.31)

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

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

package.json

@@ -121,7 +121,7 @@
     "html-webpack-plugin": "5.5.3",
     "loader-utils": "^3.2.1",
     "mini-css-extract-plugin": "2.7.6",
-    "postcss": "8.4.23",
+    "postcss": "8.4.31",
     "postcss-color-function": "4.1.0",
     "postcss-loader": "7.3.0",
     "postcss-mixins": "9.0.4",