Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires orchestra/testbench-core >=8.6.0 <8.7.0, found orchestra/testbench-core[dev-next/slim-skeleton, dev-workbench-tests-backport, dev-workbench-tests, dev-workbench-composer, dev-workbench-commands, dev-devtool, v3.4.0, ..., 3.9.x-dev, v4.0.0, ..., 4.x-dev, v5.0.0, ..., 5.x-dev, v6.0.0, ..., 6.x-dev, v7.0.0, ..., 7.x-dev, v8.0.0, ..., 8.x-dev, 9.x-dev] but it does not match the constraint.