Alpine packages for mullvad-vpn

Setup

1. Install abuild
2. Create keys: abuild-keygen The keys will end up in ~/.abuild/, and will be mounted into the build container.
3. Remember to keep keys around.

Building

./podman-build.sh ./mullvad-vpn-slint

Updating

1. Update submodule
2. Either update pkgver. If so, set pkgrel to 0, or bump pkgrel by 1.
3. git commit -m "update packages"