TestQualityMeasures' object has no attribute 'id_coins_sliced'

[KrisThielemans]

Building current CIL with the SIRF-SuperBuild works, but the tests fail with
https://github.com/SyneRBI/SIRF-SuperBuild/actions/runs/7902858550/job/21569433765?pr=862#step:11:979

ERROR: test_psnr_mask (test_quality_measures.TestQualityMeasures)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/SIRF-SuperBuild/SIRF-SuperBuild/build/sources/CIL/Wrappers/Python/test/test_quality_measures.py", line 123, in test_psnr_mask
    res1 = psnr(self.id_coins_sliced, self.id_coins_noisy_sliced)
AttributeError: 'TestQualityMeasures' object has no attribute 'id_coins_sliced'`

@MargaretDuff @paskino please have a look