Bump postcss from 8.4.30 to 8.4.31

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.30 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/8.4.30...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

package.json

@@ -61,7 +61,7 @@
     "html-webpack-plugin": "^5.5.3",
     "jest": "^26.6.3",
     "mini-css-extract-plugin": "^2.7.6",
-    "postcss": "^8.4.30",
+    "postcss": "^8.4.31",
     "postcss-loader": "^7.3.3",
     "style-loader": "^3.3.3",
     "terser-webpack-plugin": "^5.3.9",