Symfony deprecation

[dannyvw]

Method "Symfony\Component\HttpKernel\DataCollector\DataCollectorInterface::collect()" might add "void" as a native return type declaration in the future. Do the same in implementation "Doctrine\Bundle\MigrationsBundle\Collector\MigrationsCollector" now to avoid errors or add an explicit @return annotation to suppress this message.

[greg0ire]

Do you want to send a PR that does this?

[dannyvw]

#498