Your requirements could not be resolved to an installable set of packages.
Problem 1
- Root composer.json requires phpunit/phpunit ^11.3 -> satisfiable by phpunit/phpunit[11.3.0, 11.3.x-dev, 11.4.x-dev].
- phpunit/phpunit[11.3.0, ..., 11.4.x-dev] require php >=8.2 -> your php version (7.4.33) does not satisfy that requirement.
Problem 2
- orchestra/testbench[v6.0.0, ..., v6.9.0] require phpunit/phpunit ^8.4 || ^9.0 -> found phpunit/phpunit[8.4.0, ..., 8.5.x-dev, 9.0.0, ..., 9.6.x-dev] but it conflicts with your root composer.json require (^11.3).
- orchestra/testbench[v6.10.0, ..., v6.12.1] require phpunit/phpunit ^8.4 || ^9.3 -> found phpunit/phpunit[8.4.0, ..., 8.5.x-dev, 9.3.0, ..., 9.6.x-dev] but it conflicts with your root composer.json require (^11.3).
- orchestra/testbench[v6.13.0, ..., v6.21.1] require phpunit/phpunit ^8.4 || ^9.3.3 -> found phpunit/phpunit[8.4.0, ..., 8.5.x-dev, 9.3.3, ..., 9.6.x-dev] but it conflicts with your root composer.json require (^11.3).
- orchestra/testbench[v6.22.0, ..., 6.x-dev] require phpunit/phpunit ^8.5.21 || ^9.5.10 -> found phpunit/phpunit[8.5.21, ..., 8.5.x-dev, 9.5.10, ..., 9.6.x-dev] but it conflicts with your root composer.json require (^11.3).
- Root composer.json requires orchestra/testbench 6.* -> satisfiable by orchestra/testbench[v6.0.0, ..., 6.x-dev].