Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit ^4.8.35 || ^5.7 || ^6.4 || ^7.0, found phpunit/phpunit[4.8.35, 4.8.36, 5.7.0, ..., 5.7.27, 6.4.0, ..., 6.5.14, 7.0.0, ..., 7.5.20] but these were not loaded, because they are affected by security advisories ("PKSA-z3gr-8qht-p93v"). Go to https://packagist.org/security-advisories/ to find advisory details. To ignore the advisories, add their IDs to the "policy.advisories.ignore-id" config or add the package to "policy.advisories.ignore". To turn the feature off entirely, you can set "policy.advisories.block" to false.