Add parenthesis to _MigrationPrivateStorage

Author: Didayolo

src/apps/datasets/migrations/0001_initial.py

@@ -33,7 +33,7 @@ class Migration(migrations.Migration):
                 ('name', models.CharField(blank=True, max_length=255, null=True)),
                 ('type', models.CharField(choices=[('ingestion_program', 'Ingestion Program'), ('input_data', 'Input Data'), ('public_data', 'Public Data'), ('reference_data', 'Reference Data'), ('scoring_program', 'Scoring Program'), ('starting_kit', 'Starting Kit'), ('competition_bundle', 'Competition Bundle'), ('submission', 'Submission'), ('solution', 'Solution')], max_length=64)),
                 ('description', models.TextField(blank=True, null=True)),
-                ('data_file', models.FileField(blank=True, null=True, storage=_MigrationPrivateStorage, upload_to=utils.data.PathWrapper('dataset'))),
+                ('data_file', models.FileField(blank=True, null=True, storage=_MigrationPrivateStorage(), upload_to=utils.data.PathWrapper('dataset'))),
                 ('key', models.UUIDField(blank=True, default=uuid.uuid4, unique=True)),
                 ('is_public', models.BooleanField(default=False)),
                 ('upload_completed_successfully', models.BooleanField(default=False)),