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
...

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

package.json

@@ -39,7 +39,7 @@
     "needle": "^3.2.0",
     "path2d-polyfill": "^2.0.1",
     "pngjs": "^7.0.0",
-    "postcss": "^8.4.30",
+    "postcss": "^8.4.31",
     "postcss-dir-pseudo-class": "^8.0.0",
     "postcss-discard-comments": "^6.0.0",
     "postcss-nesting": "^12.0.1",