fix(deps): update dependency @next/mdx to v15.5.6

Author: renovate[bot]

package.json

@@ -13,7 +13,7 @@
     "@headlessui/react": "^2.2.9",
     "@mdx-js/loader": "^3.1.1",
     "@mdx-js/react": "^3.1.1",
-    "@next/mdx": "15.3.3",
+    "@next/mdx": "15.5.6",
     "@radix-ui/react-dialog": "^1.1.15",
     "@radix-ui/react-dropdown-menu": "^2.1.16",
     "@radix-ui/react-slot": "^1.2.3",