build: Bump laravel/framework from 12.18.0 to 12.21.0

Bumps [laravel/framework](https://github.com/laravel/framework) from 12.18.0 to 12.21.0.
- [Release notes](https://github.com/laravel/framework/releases)
- [Changelog](https://github.com/laravel/framework/blob/12.x/CHANGELOG.md)
- [Commits](laravel/framework@v12.18.0...v12.21.0)

---
updated-dependencies:
- dependency-name: laravel/framework
  dependency-version: 12.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]