chore: Bump postcss from 8.4.34 to 8.4.39 (#853)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.34 to 8.4.39.
- [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/8.4.34...8.4.39)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

package.json

@@ -39,7 +39,7 @@
     "micromatch": "^4.0.7",
     "mixin-deep": "^2.0.1",
     "node-sass": "^9.0.0",
-    "postcss": "^8.4.34",
+    "postcss": "^8.4.39",
     "regenerator-runtime": "^0.14.1",
     "sass": "^1.77.6",
     "set-value": "^4.1.0"