fix(deps): update dependency @astrojs/mdx to v4

Author: renovate[bot]

package.json

@@ -24,7 +24,7 @@
     "@astro-community/astro-embed-link-preview": "^0.2.2",
     "@astrojs/check": "^0.9.4",
     "@astrojs/cloudflare": "^11.2.0",
-    "@astrojs/mdx": "^3.1.8",
+    "@astrojs/mdx": "^4.1.1",
     "@astrojs/starlight": "^0.28.4",
     "astro": "^4.16.7",
     "astro-embed": "^0.8.0",