[skip ci] pin smriprep to stable
[skip ci] pin smriprep to stable

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