Requirements not defined

[tflori]

We came across this issue because the our library runs unit tests in the CI pipeline on php 7.1 up to php 8.0. When defining the requirement phpunit/phpunit with * it installs what ever is compatible to the current tested php version. But limedeck/phpunit-detailed-printer * always installs version 6.

In fact phpunit is not just a requirement for developement but also for production. In order to solve that every major version needs an update with the requirement of phpunit version.

If you want I can prepare some merge requests.