circleci: simplify load/pull/save of docker images using scikit-ci-addons
circleci: simplify load/pull/save of docker images using scikit-ci-addons

davidsansome/python-cmake-buildsystem,thewtex/python-cmake-buildsystem,python-cmake-buildsystem/python-cmake-buildsystem,thewtex/python-cmake-buildsystem,adrianbroher/python-cmake-buildsystem