npm: bump postcss from 8.5.19 to 8.5.20 in the postcss group

Bumps the postcss group with 1 update: [postcss](https://github.com/postcss/postcss).


Updates `postcss` from 8.5.19 to 8.5.20
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.19...8.5.20)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.20
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: postcss
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -45,7 +45,7 @@
     "@vitejs/plugin-react": "6.0.3",
     "7zip-min": "3.0.1",
     "oxlint": "1.74.0",
-    "postcss": "8.5.19",
+    "postcss": "8.5.20",
     "postcss-preset-mantine": "1.18.0",
     "postcss-simple-vars": "7.0.1",
     "typescript": "6.0.3",