release-0.8

This release makes some minor improvements to the handling of our output messages:

• Any useful/interesting output is wrapped in stars (****) to make it more apparent in the github actions UI.
• The action invokes curl to add files to the release via the Github API
  • We now pretty-print the result from the API-calls, via jq.

The only other significant change is that we abort with a non-zero exit code if the curl-call fails.

However I suspect this won't be comprehensive, because the curl command could complete and regard itself as successful even if the remote API returns "out of disk-space", "artifact already present", or some other error-condition. We're solely relying upon the exit-code that curl returns here.