赵月辉 / fastgpt-migrated

Bumps [next](https://github.com/vercel/next.js) from 15.5.18 to 15.5.21.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Commits](https://github.com/vercel/next.js/compare/v15.5.18...v15.5.21)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.5.21
  dependency-type: direct:production
...

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