Move to zstd:chunked container images

Now that zstd:chunked is supported in ostree-rs-ext and rpm-ostree (TBC), we should start pushing our container images using the zstd:chunked compression.

See also: https://fedoraproject.org/wiki/Changes/zstd:chunked

Actually making use of this will require https://github.com/containers/bootc/pull/215 or something similar.

mentioned in issue fedora/ostree/sig#26

added 1 deleted label

added Feature label

mentioned in issue #24

mentioned in issue #28

mentioned in issue #36 (closed)