Symfony 5.4 deprecations

[kedzier93]

There are a few deprecations in symfony 5.4 version with 3.5.3 ckfinder bundle.

User Deprecated: Method "Symfony\Component\HttpKernel\Bundle\Bundle::getContainerExtension()" might add "?ExtensionInterface" as a native return type declaration in the future. Do the same in child class "CKSource\Bundle\CKFinderBundle\CKSourceCKFinderBundle" now to avoid errors or add an explicit @return annotation to suppress this message.

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 "CKSource\Bundle\CKFinderBundle\Command\CKFinderDownloadCommand" now to avoid errors or add an explicit @return annotation to suppress this message.

Method "Symfony\Component\Config\Definition\ConfigurationInterface::getConfigTreeBuilder()" might add "TreeBuilder" as a native return type declaration in the future. Do the same in implementation "CKSource\Bundle\CKFinderBundle\DependencyInjection\Configuration" now to avoid errors or add an explicit @return annotation to suppress this message.

Method "Symfony\Component\Config\Definition\Builder\VariableNodeDefinition::instantiateNode()" might add "VariableNode" as a native return type declaration in the future. Do the same in child class "CKSource\Bundle\CKFinderBundle\Config\Definition\Builder\VariableArrayNodeDefinition" now to avoid errors or add an explicit @return annotation to suppress this message.

Method "Symfony\Component\Config\Definition\BaseNode::finalizeValue()" might add "mixed" as a native return type declaration in the future. Do the same in child class "CKSource\Bundle\CKFinderBundle\Config\Definition\VariableArrayNode" now to avoid errors or add an explicit @return annotation to suppress this message.

Method "Symfony\Component\Config\Definition\BaseNode::mergeValues()" might add "mixed" as a native return type declaration in the future. Do the same in child class "CKSource\Bundle\CKFinderBundle\Config\Definition\VariableArrayNode" now to avoid errors or add an explicit @return annotation to suppress this message.