Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires eliashaeussler/php-cs-fixer-config ^2.0 -> satisfiable by eliashaeussler/php-cs-fixer-config[2.0.0, ..., 2.2.1]. - Root composer.json requires phpunit/phpunit ^12.0.0 -> satisfiable by phpunit/phpunit[12.0.0, 12.0.1]. - eliashaeussler/php-cs-fixer-config[2.0.0, ..., 2.2.1] require friendsofphp/php-cs-fixer ^3.14 -> satisfiable by friendsofphp/php-cs-fixer[v3.14.0, ..., v3.68.5]. - friendsofphp/php-cs-fixer[v3.14.0, ..., v3.14.3] require sebastian/diff ^4.0 -> satisfiable by sebastian/diff[4.0.0, ..., 4.0.6]. - friendsofphp/php-cs-fixer[v3.14.4, ..., v3.49.0] require sebastian/diff ^4.0 || ^5.0 -> satisfiable by sebastian/diff[4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1]. - friendsofphp/php-cs-fixer[v3.50.0, ..., v3.66.0] require sebastian/diff ^4.0 || ^5.0 || ^6.0 -> satisfiable by sebastian/diff[4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1, 6.0.0, 6.0.1, 6.0.2]. - friendsofphp/php-cs-fixer[v3.66.1, ..., v3.68.5] require sebastian/diff ^4.0 || ^5.1 || ^6.0 -> satisfiable by sebastian/diff[4.0.0, ..., 4.0.6, 5.1.0, 5.1.1, 6.0.0, 6.0.1, 6.0.2]. - phpunit/phpunit[12.0.0, ..., 12.0.1] require sebastian/diff ^7.0.0 -> satisfiable by sebastian/diff[7.0.0]. - sebastian/diff[4.0.0, ..., 4.0.1] require php ^7.3 -> your php version (8.3.16) does not satisfy that requirement. - 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, 6.0.2, 7.0.0]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.