DEV: fixed cpu count issue in machine learning
DEV: fixed cpu count issue in machine learning

Former-commit-id: 06c4cfcff98a508f9f7632758efb37338e85ffd7
Former-commit-id: cb50f2d5e4ca03f664c34c8ec1fe84a3a2d876a7
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox