Can you please update your repo so that people can get your awesome addon using the URL feature of wowup?
If you add a release.json as an asset, it should work.

Here is sample contents:
{"releases":[{"name":"Engraver","version":"1.12.3","filename":"wowengraver-1.12.3.zip","nolib":false,"metadata":[{"flavor":"classic","interface":11500}]}]}