Upgrade postcss-dir-pseudo-class to version 10.0.0

This is a major version bump, but the changelog at
https://github.com/csstools/postcss-plugins/blob/main/plugins/postcss-dir-pseudo-class/CHANGELOG.md
doesn't indicate any breaking changes that should impact us.

We only have to list `postcss-dir-pseudo-class` in `eslint.config.js`
similar to e.g. commit a2909f9.

Author: timvandermeij

eslint.config.mjs

@@ -118,6 +118,7 @@ export default [
             "web",
             "fluent-bundle",
             "fluent-dom",
+            "postcss-dir-pseudo-class",
             "postcss-nesting",
             "postcss-values-parser",
             "stylelint",

package-lock.json

@@ -44,7 +44,7 @@
     "ordered-read-streams": "^2.0.0",
     "pngjs": "^7.0.0",
     "postcss": "^8.5.6",
-    "postcss-dir-pseudo-class": "^9.0.1",
+    "postcss-dir-pseudo-class": "^10.0.0",
     "postcss-discard-comments": "^7.0.5",
     "postcss-nesting": "^14.0.0",
     "postcss-values-parser": "^7.0.0",