CI: Use recent Python image to build packages
CI: Use recent Python image to build packages

Similarly to poldracklab/fmriprep#1790, we are changing to the Python
3.7+ docker image to test and deploy the Pypi package since twine has
stopped support for python <3.6 since their latest relase 2.0.

poldracklab/mriqc,oesteban/mriqc,poldracklab/mriqc,oesteban/mriqc,oesteban/mriqc,poldracklab/mriqc,oesteban/mriqc,poldracklab/mriqc