Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires mammatus/cron dev-0af40e37bfabc8eda81bf6ed972fc3ea7e912c4a, found mammatus/cron[dev-main] but it does not match the constraint.

Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires mammatus/cron dev-main -> satisfiable by mammatus/cron[dev-main]. - mammatus/cron dev-main requires mammatus/app dev-master -> found mammatus/app[dev-master] but it does not match your minimum-stability.