fix deprecations: use fqcn

Form/Type/ChoicesListType.php

@@ -5,6 +5,8 @@ use Symfony\Component\Form\AbstractType;
 use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\Form\FormEvent;
 use Symfony\Component\Form\FormEvents;
+use Symfony\Component\Form\Extension\Core\Type\CheckboxType;
+use Symfony\Component\Form\Extension\Core\Type\HiddenType;
 
 use Chill\MainBundle\Form\Type\TranslatableStringFormType;
 
@@ -26,10 +28,10 @@ class ChoicesListType extends AbstractType
         $locales = $this->defaultLocales;
 
         $builder->add('name', TranslatableStringFormType::class)
-            ->add('active', 'checkbox', array(
+            ->add('active', CheckboxType::class, array(
                 'required' => false
             ))
-            ->add('slug', 'hidden', array(
+            ->add('slug', HiddenType::class, array(
 
             ))
             ->addEventListener(FormEvents::SUBMIT, function(FormEvent $event) use ($locales){