Bump the development-dependencies group across 1 directory with 2 upd…

…ates

Bumps the development-dependencies group with 2 updates in the / directory: [next](https://github.com/vercel/next.js) and [rollup](https://github.com/rollup/rollup).


Updates `next` from 15.1.4 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](vercel/next.js@v15.1.4...v15.1.6)

Updates `rollup` from 4.30.1 to 4.31.0
- [Release notes](https://github.com/rollup/rollup/releases)
- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
- [Commits](rollup/rollup@v4.30.1...v4.31.0)

---
updated-dependencies:
- dependency-name: next
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: development-dependencies
- dependency-name: rollup
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: development-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>