Adds an upgrade script that automates upgrading installations on Linux from binary releases, so people don't need to reinvent the wheel. Hopefully this leads to less questions about how to upgrade, and consequently less Gitea instances running unmaintained versions in the wild.
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Norwin