root.sh: Perform dist-upgrade with the added apt repos
This ensures that we get updates from additional repos like amber-security in the image out-of-box.
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
apt apt-utils bsdutils ca-certificates fdisk libapt-inst2.0 libapt-pkg5.0 libblkid1 libc-bin libc6 libfdisk1
libmount1 libsmartcols1 libssl1.1 libudev1 libuuid1 mount multiarch-support openssl pureos-minimal sudo
systemd-sysv tzdata udev util-linux
25 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.