Remove snap packaging from repository
I've merged this !552 (merged) but I'm not sure if we should keep the snap in this repository or if it'll better to just move that to a different one. Because if we add more packaging configurations, we can add here the AUR, deb, rpm, etc and I think it's not needed.
Maybe we should keep only the flatpak as official maintained package and let third parties to create other packagins outside this repository and just add links in the README.md in a different section.