chore(deps-dev): 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

@@ -56,7 +56,7 @@
     "markdownlint-cli": "^0.37.0",
     "marked": "^9.0.3",
     "pagefind": "^1.0.3",
-    "postcss": "^8.4.30",
+    "postcss": "^8.4.31",
     "prettier": "^3.0.3",
     "prettier-plugin-tailwindcss": "^0.5.4",
     "rss-parser": "^3.13.0",