Not support old version DICOM

[doumeng]

No DICOM magic number found, but the file appears to be DICOM without a preamble.
Proceeding without caution.No DICOM magic number found, but the file appears to be DICOM without a preamble.
Proceeding without caution.

solution:
use dcmread force=True, and
`def load_dcm_images_from_path(dicom_series_path: str) -> List[Dataset]:
series_data = []
for root, _, files in os.walk(dicom_series_path):
for file in files:
try:
ds = dcmread(os.path.join(root, file), force=True)
if hasattr(ds, 'PixelData'):
series_data.append(ds)

        except Exception:
            # Not a valid DICOM file
            continue

return series_data`

and delete the validation function
` def create_from(dicom_series_path: str, rt_struct_path: str) -> RTStruct:
"""
Method to load an existing rt struct, given related DICOM series and existing rt struct
"""

    series_data = image_helper.load_sorted_image_series(dicom_series_path)
    ds = dcmread(rt_struct_path)
    # RTStructBuilder.validate_rtstruct(ds)
    # RTStructBuilder.validate_rtstruct_series_references(ds, series_data)

    # TODO create new frame of reference? Right now we assume the last frame of reference created is suitable 
    return RTStruct(series_data, ds)`