build(deps-dev): bump barryvdh/laravel-debugbar from 3.6.7 to 3.6.8

Bumps [barryvdh/laravel-debugbar](https://github.com/barryvdh/laravel-debugbar) from 3.6.7 to 3.6.8.
- [Release notes](https://github.com/barryvdh/laravel-debugbar/releases)
- [Changelog](https://github.com/barryvdh/laravel-debugbar/blob/master/changelog.md)
- [Commits](barryvdh/laravel-debugbar@v3.6.7...v3.6.8)

---
updated-dependencies:
- dependency-name: barryvdh/laravel-debugbar
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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