Bump next from 15.5.7 to 15.5.9 (#72)

Bumps [next](https://github.com/vercel/next.js) from 15.5.7 to 15.5.9.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.5.7...v15.5.9)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.5.9
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -19,7 +19,7 @@
     "highlight.js": "^11.10.0",
     "jszip": "^3.10.1",
     "nbtify": "^2.2.0",
-    "next": "^15.5.7",
+    "next": "^15.5.9",
     "next-themes": "^0.4.6",
     "react": "^19.1.2",
     "react-dom": "^19.1.2",