Bump laravel/dusk from 6.13.0 to 6.21.0

Bumps [laravel/dusk](https://github.com/laravel/dusk) from 6.13.0 to 6.21.0.
- [Release notes](https://github.com/laravel/dusk/releases)
- [Changelog](https://github.com/laravel/dusk/blob/6.x/CHANGELOG.md)
- [Commits](laravel/dusk@v6.13.0...v6.21.0)

---
updated-dependencies:
- dependency-name: laravel/dusk
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]