Bump postcss-custom-media from 10.0.8 to 12.0.1

Bumps [postcss-custom-media](https://github.com/csstools/postcss-plugins/tree/HEAD/plugins/postcss-custom-media) from 10.0.8 to 12.0.1.
- [Changelog](https://github.com/csstools/postcss-plugins/blob/main/plugins/postcss-custom-media/CHANGELOG.md)
- [Commits](https://github.com/csstools/postcss-plugins/commits/HEAD/plugins/postcss-custom-media)

---
updated-dependencies:
- dependency-name: postcss-custom-media
  dependency-version: 12.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package-lock.json

@@ -21,7 +21,7 @@
     "headroom.js": "^0.12.0",
     "mini-css-extract-plugin": "^2.10.1",
     "postcss": "^8.5.8",
-    "postcss-custom-media": "^10.0.2",
+    "postcss-custom-media": "^12.0.1",
     "postcss-loader": "^8.2.1",
     "sass": "1.91.0",
     "sass-loader": "^16.0.7",