Automate the release workflow using GitHub actions
This introduces a two-part release mechanism. A manually triggered
workflow asks for the important info like type of release (stable, rc)
and code name. It then creates a cleanly mergable pull request.
When that pull request is merged, a release is automatically tagged,
built and uploaded.
Another workflow is introduced to keep track of the deleted.files info.
This is one less chore to do on a release.
A new scheme for tags is also introduced, making all tags sortable,
regardless of their type. They follow the pattern
release-YYYY-MM-DD(<hotfixletter>|rc)
A script will be used to clean-up the existing tags.