support for RTSTRUCT modalities

[hosseinjafar]

Hi,

While trying to load a DICOM structure file (dataset.Modality == RTSTRUCT), I get an error saying:
ValueError: DICOM dataset is not a DICOM-SEG storage

After digging into the code I see that in pydicom-seg/pydicom_seg/reader.py line 110, the code checks if the dataset.Modality is "SEG".
if dataset.SOPClassUID != SegmentationStorage or dataset.Modality != "SEG": raise ValueError("DICOM dataset is not a DICOM-SEG storage")

I was wondering if there is plans to add support for RTSTRUCT files? there is a slicer script that converts RTSTRUCT to SEG, but it would be nice to support these files.