fix confounds workflow test
fix confounds workflow test

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