Add missing file for flutter

Author: abnegate

src/SDK/Language/Flutter.php

@@ -60,6 +60,11 @@ public function getFiles(): array
                 'destination'   => '/lib/models.dart',
                 'template'      => 'dart/lib/models.dart.twig',
             ],
+            [
+                'scope'         => 'default',
+                'destination'   => '/lib/enums.dart',
+                'template'      => 'dart/lib/enums.dart.twig',
+            ],
             [
                 'scope'         => 'default',
                 'destination'   => '/lib/permission.dart',