Drop support of unmaintained versions of Symfony

[franmomu]

This includes Symfony 4.4, 6.0 and 6.1

These versions are unmaintained (4.4 is only getting security fixes). I wanted to see how much code was involved and looks like it isn't that much, so I'm also fine if we don't remove support in 4.6.0.

[IonBazan]

Is it the right moment to add native return types to Commands and other classes?

[GromNaN]

Is it the right moment to add native return types to Commands and other classes?

This is off-topic and should be addressed in an other issue/pr.

Adding return types is a breaking change according to Symfony's BC policy. But the @return phpdoc should be updated so that types can be upgraded in the next major. The Symfony process was documented here.

[IonBazan]

@GromNaN Thanks for clarification. I assume we can leave the ones applied in @internal classes then.