Add a CI workflow to run pytest nightly

[charlesyuan314]

This workflow runs check/pytest (all tests) at 4:00 AM PT (11:00 AM UTC) every Monday-Friday.

It can be a first step toward reducing the runtime of pytest on pull requests.

[charlesyuan314]

Note from GitHub:

When the last user to commit to the cron schedule of a workflow is removed from the organization, the scheduled workflow will be disabled. If a user with write permissions to the repository makes a commit that changes the cron schedule, the scheduled workflow will be reactivated. Note that, in this situation, the workflow is not reactivated by any change to the workflow file; you must alter the cron value and commit this change.

[mpharrigan]

what counts as a user committing? if I press the merge button is it me?

[charlesyuan314]

Yes, I think you are a committer if you press merge.

[charlesyuan314]

To be safe, I think you should also press squash-and-merge on the PR so you show up as coauthor of the PR in the commit log.

[mpharrigan]

To be safe, I think you should also press squash-and-merge on the PR so you show up as coauthor of the PR in the commit log.

sorry, that's the button I meant. I think i'll be the "committer" but you will be the "author"