Your requirements could not be resolved to an installable set of packages. Problem 1 - phpstan/extension-installer is locked to version 1.4.3 and an update of this package was not requested. - phpstan/extension-installer 1.4.3 requires php ^7.2 || ^8.0 -> your php version (7.1.33) does not satisfy that requirement. Problem 2 - phpstan/phpstan is locked to version 1.12.11 and an update of this package was not requested. - phpstan/phpstan 1.12.11 requires php ^7.2|^8.0 -> your php version (7.1.33) does not satisfy that requirement. Problem 3 - phpstan/phpstan-deprecation-rules is locked to version 1.2.1 and an update of this package was not requested. - phpstan/phpstan-deprecation-rules 1.2.1 requires php ^7.2 || ^8.0 -> your php version (7.1.33) does not satisfy that requirement. Problem 4 - phpstan/phpstan-phpunit is locked to version 1.4.1 and an update of this package was not requested. - phpstan/phpstan-phpunit 1.4.1 requires php ^7.2 || ^8.0 -> your php version (7.1.33) does not satisfy that requirement. Problem 5 - phpstan/phpstan-strict-rules is locked to version 1.6.1 and an update of this package was not requested. - phpstan/phpstan-strict-rules 1.6.1 requires php ^7.2 || ^8.0 -> your php version (7.1.33) does not satisfy that requirement.