sct_process_segmentation.py: Add missing type information (#3039)
sct_process_segmentation.py: Add missing type information (#3039)

Fixes bug where int (e.g. 1) is parsed a str ('1')
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox