GitHub action to generate coverage report, with badge

[DonalChilde]

Figure out how to run coverage as a github action, and save result for use in a badge. reference: http://schneegans.github.io/tutorials/2022/04/18/badges https://nedbatchelder.com/blog/202209/making_a_coverage_badge.html https://dev.to/thejaredwilcurt/coverage-badge-with-github-actions-finally-59fa https://github.com/we-cli/coverage-badge-action

[fritx]

@DonalChilde hey if you are using Pytest, this fork seems to work: https://github.com/we-cli/coverage-badge-action/pull/3/files https://github.com/llueder/coverage-badge-action-pytest/actions