fix setting mem_gb
fix setting mem_gb

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