Tutorials are not included in the documentation reliably

[jobrachem]

I just took a look at our documentation page and was surprised to see that the tutorials were missing. This apparently happened after merging https://github.com/liesel-devs/liesel/pull/57

The docs action ran successfully as expected and did trigger a build. However, the RTD output includes the following line:

WARNING: rtds_action: can't find expected artifact 'tutorials-for-a96501eac22b5137043654698811a55f90b8cac8' at https://api.github.com/repos/liesel-devs/liesel/actions/artifacts

The artifacts, however, are present, as can be seen here: https://github.com/liesel-devs/liesel/actions/runs/4556491906

My only real theory for why this might happen is some sort of racing condition between the steps "Upload artifacts" and "Trigger RTD build". I have just triggered a new documentation build manually to see whether the tutorials are included now.

[jobrachem]

Testing is currently blocked because of a dependency bug. This can move forward after #60 is merged.

[jobrachem]

With the new build, the tutorials are back up. I think at the moment this issue is a bit annoying, but not a huge problem.