Merge branch 'add-flake8-checker' into 'master'

.gitlab-ci.yml

cli_tupak/plot_multiple_posteriors.py

setup.cfg

setup.py

tupak/core/__init__.py

tupak/core/likelihood.py

tupak/core/prior.py

tupak/core/result.py

tupak/core/sampler.py

tupak/core/utils.py

tupak/gw/calibration.py

tupak/gw/conversion.py

tupak/gw/detector.py

tupak/gw/likelihood.py

tupak/gw/source.py

tupak/gw/utils.py

tupak/hyper/likelihood.py