readPlist removed in python 3.9 - unable to use ImportOsirix ROI

[fedorov]

As discussed in https://discourse.slicer.org/t/problems-using-importosirixroi-from-the-sandbox-extension/31406, ImportOsirixROI functionality appears to be broken.

"[...]/AppData/Local/slicer.org/Slicer 5.4.0/slicer.org/Extensions-31938/Sandbox/lib/Slicer-5.4/qt-scripted-modules/ImportOsirixROI.py", line 284, in importOsirixRoiFileToSegmentation

[CRITICAL][Stream] 28.08.2023 11:25:17 [] (unknown:0) -     inputRoiData = plistlib.readPlist(inputRoi)

[CRITICAL][Stream] 28.08.2023 11:25:17 [] (unknown:0) - AttributeError: module 'plistlib' has no attribute 'readPlist'