LSSTDataset return values should be numpy

[drewoldag]

Audit the LSSTDataset classes and make sure that the values that they are returning are numpy not torch tensors.

[drewoldag]

I think this may be just fine. There's only one getter in these dataset classes to return an image.

The image is sent to self.apply_transform, which returns a numpy object.

[drewoldag]

Double checked the code path and it seems that there are only two getters for LSSTDataset and DownloadLSSTDataset, namely get_image and get_objectId.

get_objectId always returns a string ✅
get_image always the output from self.apply_transform which will return data_transformed.numpy(). i.e. numpy ✅

So I think we're good here.