chore(deps): bump postcss from 5.2.18 to 8.4.31 (#3952)

Bumps [postcss](https://github.com/postcss/postcss) from 5.2.18 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/commits/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>

package.json

@@ -139,7 +139,7 @@
     "less": "^4.1.1",
     "lodash": "^4.17.21",
     "npm-run-all": "^4.1.5",
-    "postcss": "^8.4.20",
+    "postcss": "^8.4.31",
     "postcss-less": "^6.0.0",
     "prettier": "^2.8.0",
     "pretty-quick": "^3.1.1",