Fix a deprecation in console command return types

[javiereguiluz]

Q	A
Type	improvement
BC Break	no
Fixed issues	-

Summary

This is needed to fix the following deprecation:

  1x: Method "Symfony\Component\Console\Command\Command::execute()" might add "int" as a native return type declaration in the future. Do the same in child class "Doctrine\DBAL\Tools\Console\Command\RunSqlCommand" now to avoid errors or add an explicit @return annotation to suppress this message.
    1x in AddUserCommandTest::testCreateUserNonInteractive from App\Tests\Command

[derrabus]

Thank you, @javiereguiluz!