fix: add placeholders for fields nationality and country

src/Form/PersonalDataType.php

@@ -52,11 +52,13 @@ class PersonalDataType extends AbstractType
             ])
             ->add('country', CountryType::class, [
                 'label' => 'Land',
+                'placeholder' => 'Bitte auswählen...',
                 'property_path' => 'address.country',
             ])
             ->add('nationality', CountryType::class, [
                 'label' => 'Nationalität',
                 'property' => 'nationality',
+                'placeholder' => 'Bitte auswählen...',
                 'preferred_choices' => ['D', 'A', 'CH'],
             ])
             ->add('email', EmailType::class, [