fix: get mdc configs by calling mdc:configSources hook (#3736)

Co-authored-by: Farnabaz <farnabaz@gmail.com>

Author: danielroe

package.json

@@ -60,7 +60,7 @@
   },
   "dependencies": {
     "@nuxt/kit": "^4.4.2",
-    "@nuxtjs/mdc": "^0.20.1",
+    "@nuxtjs/mdc": "^0.21.0",
     "@shikijs/langs": "^4.0.2",
     "@sqlite.org/sqlite-wasm": "3.50.4-build1",
     "@standard-schema/spec": "^1.1.0",