Encrypted images don't resize root partition

luks encrypted images don't resize / on first boot - it would be a nice addition to fix this in cloud-initramfs-growroot (for Debian too)

This is likely not necessary due to https://source.puri.sm/Librem5/Apps_Issues/-/issues/200 / calamares doing the on device work later on but in case somebody wants to fix it let's make it obvious that this is bug.