Your requirements could not be resolved to an installable set of packages.
Problem 1
- phpunit/phpunit[11.0.0, ..., 11.3.6] require php >=8.2 -> your php version (8.1.29) does not satisfy that requirement.
- Root composer.json requires phpunit/phpunit ^11 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.3.6].