Bump next from 15.5.5 to 15.5.6

Bumps [next](https://github.com/vercel/next.js) from 15.5.5 to 15.5.6.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.5.5...v15.5.6)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.5.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

package.json

@@ -18,7 +18,7 @@
     "@mui/material": "^5.18.0",
     "@mui/styles": "^6.5.0",
     "firebase": "^12.4.0",
-    "next": "^15.5.5",
+    "next": "^16.0.0",
     "react": "^18.2.0",
     "react-dom": "^18.3.1"
   },