composer(deps-dev): update orchestra/testbench requirement
composer(deps-dev): update orchestra/testbench requirement

Updates the requirements on [orchestra/testbench](https://github.com/orchestral/testbench) to permit the latest version.
- [Release notes](https://github.com/orchestral/testbench/releases)
- [Changelog](https://github.com/orchestral/testbench/blob/6.x/CHANGELOG-6.x.md)
- [Commits](https://github.com/orchestral/testbench/compare/v6.11.0...v6.12.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
codedge/laravel-fpdf,codedge/laravel-fpdf