Bump @next/mdx from 15.1.0 to 15.1.6

Bumps [@next/mdx](https://github.com/vercel/next.js/tree/HEAD/packages/next-mdx) from 15.1.0 to 15.1.6.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](https://github.com/vercel/next.js/commits/v15.1.6/packages/next-mdx)

---
updated-dependencies:
- dependency-name: "@next/mdx"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

package.json

@@ -23,7 +23,7 @@
   "dependencies": {
     "@auth0/nextjs-auth0": "^3.5.0",
     "@neondatabase/serverless": "^0.10.4",
-    "@next/mdx": "15.1.0",
+    "@next/mdx": "15.1.6",
     "@react-pdf-viewer/core": "^3.12.0",
     "@react-pdf-viewer/default-layout": "^3.12.0",
     "@tanstack/react-table": "^8.20.5",