Bugfix: Birthday can be stored

app/Repositories/UserRepository.php

@@ -93,6 +93,7 @@ class UserRepository {
             'first_aid_permission' => $request->firstAidPermission,
             'bank_account_owner'  => $request->bankAccountOwner,
             'bank_account_iban'   => $request->bankAccountIban,
+            'birthday'            => $request->birthday,
         ]);
     }
 }