`include_dummies` option should be on in standard VG dataset training

[LeoXing1996]

In preprocess_packed_vg.py, min_relationships_per_image option is set as 0 and preverse some images without relationships (self.data['relationships_per_image][index] == 0).

However, in sg2im/data/vg.py, images without relationships may have empty triplets and lead to an error in the following code.

https://github.com/roeiherz/CanonicalSg2Im/blob/6aa2812c7c4a8d82794285ed305e20f43ca9de1d/sg2im/data/base_dataset.py#L100

Should this option be set as True in standard VG dataset training? Or I do something wrong?