feat: update filter value to be inversed

closes #869bhe07h

src/Form/AssignmentFilterType.php

@@ -63,8 +63,8 @@ class AssignmentFilterType extends AbstractType
                 'label' => 'vergangene Einsätze anzeigen',
                 'required' => false,
             ])
-            ->add('syncedWithBusProNet', CheckboxType::class, [
-                'label' => 'in BusProNet hinterlegt',
+            ->add('notSyncedWithBusProNet', CheckboxType::class, [
+                'label' => 'nicht in BusProNet hinterlegt',
                 'required' => false,
             ])
             ->add('country', ChoiceType::class, [