- switch to POSIX shell
 - set -u
 - make shellcheck clean
 - avoid cd in favour of -C and env --chdir
 - bump u-boot version from v2023.10-rc4 to v2023.10
 - verify top git hashes for u-boot and atf
 - verify that BPI Block Copy src is correct for sd and emmc
 - verify that sd and emmc images differ only in the Block Copy src

config: set bootargs to the same values as flash-kernel/ubootenv.d/00reform2_ubootenv for ls1028a

See merge request !2

.gitlab-ci.yml: install python3, bc

See merge request !1