Report pytest results back to Github

[volcacius]

Currently Github Actions don't support any standardized way to report back test results. It should be doable to it manually by exporting to junit xml format and then calling appropriate Github APIs.
In particular, it would be nice if we could link a test failure back to the line of code that caused it.

References:
https://github.community/t5/GitHub-Actions/Reporting-Summary-of-test-failures/td-p/36868
https://tryexceptpass.org/article/pytest-github-integration/
https://stackoverflow.com/questions/60126813/github-actions-report-dotnet-test-result-as-annotations
https://github.com/pytorch/add-annotations-github-action

[volcacius]

Reporting back to sphinx might be an option with https://sphinx-test-reports.readthedocs.io/en/latest/ .