[Merge] ~xypron/livecd-rootfs:milkv-mars into livecd-rootfs:ubuntu/master

[Łukasz Zemczak]

Review: Approve

I think we need to one day revamp the RISC-V builds, maybe even using ubuntu-image/imagecraft. But other than that, the changes look fine. Merging and releasing.
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https://code.launchpad.net/~xypron/livecd-rootfs/+git/livecd-rootfs/+merge/462019
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