Add `return void` annotation to silence deprecation msg

[PhilETaylor]

can you please send a PR to add the @return void annotation? That's enough to express the intent and fix the deprecation.

ref https://github.com/doctrine/DoctrineFixturesBundle/pull/381#issuecomment-1502825960

Used single/one line annotation syntax as proposed elsewhere

//cc @nicolas-grekas

[derrabus]

Thank you!