Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires silverstripe/installer 6.x-dev -> satisfiable by silverstripe/installer[6.x-dev]. - silverstripe/installer 6.x-dev requires silverstripe/recipe-cms 6.x-dev -> satisfiable by silverstripe/recipe-cms[6.x-dev]. - silverstripe/recipe-cms 6.x-dev requires silverstripe/recipe-core 6.x-dev -> satisfiable by silverstripe/recipe-core[6.x-dev]. - silverstripe/recipe-core 6.x-dev requires silverstripe/mimevalidator 4.x-dev -> satisfiable by silverstripe/mimevalidator[4.x-dev] from composer repo (https://repo.packagist.org) but silverstripe/mimevalidator 4.0.x-dev is the root package and cannot be modified. See https://getcomposer.org/dep-on-root for details and assistance.

Process completed with exit code 2.