fix deprecation: no more passing of type instances

Form/ActivityType.php

@@ -17,6 +17,7 @@ use Symfony\Component\Form\FormEvents;
 use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
 use Symfony\Component\Form\Extension\Core\Type\TextareaType;
 use Symfony\Component\Form\Extension\Core\Type\DateTimeType;
+use Symfony\Component\Form\Extension\Core\Type\DateType;
 use Chill\ActivityBundle\Form\Type\TranslatableActivityType;
 use Chill\ActivityBundle\Form\Type\TranslatableActivityReason;
 
@@ -90,7 +91,7 @@ class ActivityType extends AbstractType
         );
 
         $builder
-            ->add('date', 'date', array(
+            ->add('date', DateType::class, array(
                'required' => true,
                'widget' => 'single_text',
                'format' => 'dd-MM-yyyy')