Your requirements could not be resolved to an installable set of packages. Problem 1 - sebastian/diff[4.0.0, ..., 4.0.1] require php ^7.3 -> your php version (8.3.3) does not satisfy that requirement. - Root composer.json requires phpunit/phpunit ^11.0.0 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.0.6]. - psalm/plugin-phpunit 0.19.0 requires vimeo/psalm dev-master || ^5@beta || ^5.0 -> satisfiable by vimeo/psalm[5.15.0, ..., 5.23.1]. - vimeo/psalm[5.22.0, ..., 5.23.1] require nikic/php-parser ^4.16 -> satisfiable by nikic/php-parser[v4.16.0, v4.17.0, v4.17.1, v4.18.0]. - You can only install one version of a package, so only one of these can be installed: nikic/php-parser[v4.16.0, v4.17.0, v4.17.1, v4.18.0, v5.0.0, v5.0.1, v5.0.2]. - vimeo/psalm[5.15.0, ..., 5.21.1] require sebastian/diff ^4.0 || ^5.0 -> satisfiable by sebastian/diff[4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1]. - phpunit/php-code-coverage[11.0.0, ..., 11.0.3] require nikic/php-parser ^5.0 -> satisfiable by nikic/php-parser[v5.0.0, v5.0.1, v5.0.2]. - You can only install one version of a package, so only one of these can be installed: sebastian/diff[4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1, 6.0.0, 6.0.1]. - phpunit/phpunit[11.0.0, ..., 11.0.6] require phpunit/php-code-coverage ^11.0 -> satisfiable by phpunit/php-code-coverage[11.0.0, 11.0.1, 11.0.2, 11.0.3]. - phpunit/phpunit[11.0.0, ..., 11.0.6] require sebastian/diff ^6.0 -> satisfiable by sebastian/diff[6.0.0, 6.0.1]. - Root composer.json requires psalm/plugin-phpunit ^0.19.0 -> satisfiable by psalm/plugin-phpunit[0.19.0]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.