Take morph map into account (#15)

Translate FQCN into class alias from morph map

Author: buddhaCode

src/Morph.php

@@ -107,7 +107,7 @@ protected function queryCleanOrphan(Model $parentModel, Relation $relation, bool
         $method = $dryRun ? 'count' : 'delete';
 
         return DB::table($childTable)
-                ->where($childFieldType, get_class($parentModel))
+                ->where($childFieldType, $parentModel->getMorphClass())
                 ->whereNotExists(function ($query) use (
                     $parentModel,
                     $childTable,