Bump postcss from 8.4.27 to 8.4.31 (#287)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.27 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@8.4.27...8.4.31)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package.json

@@ -23,7 +23,7 @@
     "autoprefixer": "^10.4.14",
     "globby": "^13.2.2",
     "jstransformer-lowlight": "^0.1.0",
-    "postcss": "^8.4.27",
+    "postcss": "^8.4.31",
     "postcss-hexrgba": "^2.1.0",
     "postcss-media-minmax": "^5.0.0",
     "postcss-nested": "^6.0.1",