Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires chevere/filesystem ^1.0.x-dev -> satisfiable by chevere/filesystem[1.0.x-dev]. - chevere/filesystem 1.0.x-dev requires chevere/parameter ^1.0.x-dev -> found chevere/parameter[1.0.x-dev] but it does not match your minimum-stability.