Bump next in /frontend in the npm_and_yarn group across 1 directory

Bumps the npm_and_yarn group with 1 update in the /frontend directory: [next](https://github.com/vercel/next.js).


Updates `next` 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
  dependency-group: npm_and_yarn
...

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

Author: dependabot[bot]

frontend/package.json

@@ -29,7 +29,7 @@
     "eslint-config-next": "15.1.3",
     "formik": "^2.4.6",
     "jest": "^29.7.0",
-    "next": "^15.5.7",
+    "next": "^15.5.9",
     "next-router-mock": "^0.9.13",
     "postcss": "^8.5.4",
     "react": "19.0.0",