fix deprecations: use choices_as_values=true and flip content of the choice options

Export/Filter/GenderFilter.php

@@ -50,9 +50,10 @@ class GenderFilter implements FilterInterface,
     {
         $builder->add('accepted_genders', ChoiceType::class, array(
             'choices' => array(
-                Person::FEMALE_GENDER => 'Woman',
-                Person::MALE_GENDER   => 'Man'
+                'Woman' => Person::FEMALE_GENDER,
+                'Man' => Person::MALE_GENDER
             ),
+            'choices_as_values' => true,
             'multiple' => false,
             'expanded' => false
         ));