add test for --skip-vols-num
add test for --skip-vols-num

poldracklab/fmriprep,oesteban/preprocessing-workflow,oesteban/preprocessing-workflow,poldracklab/preprocessing-workflow,oesteban/fmriprep,poldracklab/fmriprep,poldracklab/fmriprep,poldracklab/preprocessing-workflow,oesteban/fmriprep,oesteban/fmriprep