Revamp ci

[tomlechner]

Currently there's a travis based continuous build, which was made before github actions really worked. Travis is fine, but it's one extra step to maintain as github seems to want to change its auth schemes a lot.

Unless there's some better option, for ease of releasing, CI builds should instead be built with github actions. Ideally there would be one path for automatic appimage builds on pushes to master, and also one path for more build types when there's a tag for a new version release of Laidout.

For full releases, it would be nice to produce at least the following:

• source tarball
• tarball with compiled executable
• appimage
• flatpak
• .deb targeting fairly recent Ubuntu
• .deb targeting Debian Stable

I briefly started some work for this in the ci-test branch, but it needs a ton of work.

[AkiSakurai]

fyr, here is modified workflow that also build macos tar.

https://github.com/AkiSakurai/Laidout-Action/actions/runs/2964629996/workflow

[tomlechner]

I don't suppose you know how to automatically take the artifact and push it to particular Releases? The travis method uses https://github.com/probonopd/uploadtool/, but I haven't had time to figure out what it's actually doing.