Your requirements could not be resolved to an installable set of packages.
Problem 1
- phpunit/phpunit[9.0.0, ..., 9.2.6] require php ^7.3 -> your php version (7.2.34) does not satisfy that requirement.
- phpunit/phpunit[9.3.0, ..., 9.3.8] require php ^7.3 || ^8.0 -> your php version (7.2.34) does not satisfy that requirement.
- phpunit/phpunit[9.3.9, ..., 9.6.13] require php >=7.3 -> your php version (7.2.34) does not satisfy that requirement.
- Root composer.json requires phpunit/phpunit ^9 -> satisfiable by phpunit/phpunit[9.0.0, ..., 9.6.13].