Bump postcss from 8.4.27 to 8.4.31 in /ui-tests (#124)

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: indirect
...

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

ui-tests/yarn.lock

@@ -3244,13 +3244,13 @@ __metadata:
   linkType: hard
 
 "postcss@npm:^8.3.11":
-  version: 8.4.27
-  resolution: "postcss@npm:8.4.27"
+  version: 8.4.31
+  resolution: "postcss@npm:8.4.31"
   dependencies:
     nanoid: ^3.3.6
     picocolors: ^1.0.0
     source-map-js: ^1.0.2
-  checksum: 1cdd0c298849df6cd65f7e646a3ba36870a37b65f55fd59d1a165539c263e9b4872a402bf4ed1ca1bc31f58b68b2835545e33ea1a23b161a1f8aa6d5ded81e78
+  checksum: 1d8611341b073143ad90486fcdfeab49edd243377b1f51834dc4f6d028e82ce5190e4f11bb2633276864503654fb7cab28e67abdc0fbf9d1f88cad4a0ff0beea
   languageName: node
   linkType: hard