Use workflow artifacts for debugging failed tests in CI.

[jgaehring]

From https://github.com/farmOS/farmOS.js/issues/43#issuecomment-930333654 and subsequent comments:

• https://docs.github.com/en/actions/managing-workflow-runs/downloading-workflow-artifacts
• https://github.com/actions/upload-artifact
• https://docs.github.com/en/actions/monitoring-and-troubleshooting-workflows/enabling-debug-logging

Maybe for now I'll just write something up that dumps some JSON from any errors that halt a test from running. Could be helpful for issues like this that happen in the future, where it's not the test per se that fails, but rather compatibility issue.

[jgaehring]

Oops, didn't realize I had this duplicate of #46.