chore(deps): bump @next/mdx from 14.2.21 to 15.1.2

Bumps [@next/mdx](https://github.com/vercel/next.js/tree/HEAD/packages/next-mdx) from 14.2.21 to 15.1.2.
- [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/v15.1.2/packages/next-mdx)

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

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

package.json

@@ -16,7 +16,7 @@
         "@headlessui/tailwindcss": "^0.2.1",
         "@mdx-js/loader": "^3.0.1",
         "@mdx-js/react": "^3.0.1",
-        "@next/mdx": "^14.2.13",
+        "@next/mdx": "^15.1.2",
         "@sindresorhus/slugify": "^2.2.1",
         "@tailwindcss/typography": "^0.5.15",
         "@types/mdx": "^2.0.13",