Utilize Github Releases tab for versioned releases

Problem

Right now, packaging the app into existing repositories can only be done by either manually going to fluxer.app and downloading the source code or appimage before packaging it, or pulling the latest git commit from the repo, which isn't ideal for non-testing packaging.

Proposed solution

Utilize the Releases feature built into GitHub to allow for all files related to a specific version to be logged in an easily accessible place, as it pins a specific commit from the Git history that can be tracked by continuous integration systems such as Hydra from Nix.