NLMTB_Dataset cannot be run without images

[josephdviviano]

Traceback (most recent call last):
  File "/home/mila/v/vivianoj/code/torchxrayvision/scripts/train_model.py", line 131, in <module>
    dataset = xrv.datasets.NLMTB_Dataset(
  File "/home/mila/v/vivianoj/code/torchxrayvision/scripts/../torchxrayvision/datasets.py", line 1356, in __init__
    for fname in sorted(os.listdir(os.path.join(self.imgpath, "CXR_png"))):
FileNotFoundError: [Errno 2] No such file or directory: './CXR_png'