Your requirements could not be resolved to an installable set of packages. Problem 1 - phpstan/phpstan-phpunit[1.1.0, ..., 1.4.0] require php ^7.2 || ^8.0 -> your php version (7.1.33) does not satisfy that requirement. - Root composer.json requires phpstan/phpstan-phpunit ^1.1 -> satisfiable by phpstan/phpstan-phpunit[1.1.0, ..., 1.4.0].