Package updates

[nazar-pc]

Not sure if it would be worth it to build updater infrastructure, though depending on options chosen for #6 (OBS), #7 (Homebrew) and Windows (Chocolatey) it might be possible to get this cheaply.

Either way the first step would be to add functionality to check availability of a newer release on GitHub periodically and show something to the user so that they can go and download new version, which shouldn't be too difficult. Desktop notifications would be especially nice here since application can be minimized.

[nazar-pc]

MSIX on Windows can apparently support auto-updates, didn't look into it very closely though.

[nazar-pc]

For now the following should be done:

• downloading https://api.github.com/repos/nazar-pc/space-acres/releases/latest (with reqwest, URL might also be inferred from repository in Cargo.toml so it works in forks too and is not hardcoded)
• checking tag_name field
• try to parse it with semver
• compare with the version of the app itself
• in case new version is newer, show it somewhere with a link to releases