Handle release upgrade
Right now, the stable channel is on the v20.05 branch. We want to create a new postmarketOS release branch at some point (e.g. when Alpine makes a new release), then we'll need a sane way (CLI and GUI) to upgrade from one release to another.
Apparently there is some support in GNOME software for it, as seen in the Fedora wiki and mentioned in the gnome-software changelog:
Version 3.19.90
~~~~~~~~~~~~~~~
Released: 2016-02-15
This is an unstable release in the 3.19 development series, with the following
improvements:
* Add end-user application review functionality
* Add support for upgrading the OS from one release to another
...I haven't looked into the details yet. In theory it should check if the currently installed packages are all available in the next release, possibly with a list of what's safe to remove, then ask the user if it's fine for them to remove these packages (let's say their favorite app was dropped) and then execute the upgrade.
https://wiki.alpinelinux.org/wiki/Upgrading_Alpine#Upgrading_to_latest_release
CC: @cogitri