Bump postcss from 8.4.17 to 8.4.31 (#1267)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.17 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@8.4.17...8.4.31)

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

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

Author: dependabot[bot]

package-lock.json

@@ -335,7 +335,7 @@
     "bytes": "^3.1.2",
     "css-loader": "^6.7.1",
     "file-loader": "^6.2.0",
-    "postcss": "^8.4.17",
+    "postcss": "^8.4.31",
     "postcss-loader": "^6.2.1",
     "process": "0.11.10",
     "sass": "^1.55.0",