have the dependents test test all dependents

[wchristian]

this was previously a pull request in #292 however, i resolved it by way of completing the work on #e527641483403f5b0cd88507862cf1ffc0550197 which makes dependents tests available under https://github.com/Perl-Critic/PPI/actions/workflows/test-dependents.yml

more work is to be done though, since this only tests the first layer of dependents

@wolfsage has a module to resolve these things better, but it is as of yet not available on cpan :)