Github Actions archive upload. Compress files prior to upload.

Description of problem:

The github actions step "Publish Releases as Artifacts" generates this error - "There are over 10,000 files in this artifact, consider creating an archive before upload to improve the upload performance." It takes 34 minutes, which is slow.

Search the upload-artifact repository for issues:
https://github.com/actions/upload-artifact/issues/

`is:issue zip archive`

Multiple results. Issue 39 "upload-artifact double-zips a zip", says that upload-artifact double-zips a zip.

Possible solutions:
- tar (rather than zip) the files before proceeding.
- wait for a better solution from Issue 39. No action at the moment.