This mainly pulls in the latest support for zstd-compressed layers and
eases testing of containers/image.
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>
Anyone running (vndr) currently ends up with failing tests in OCI schema
validation because gojsonschema has fixed its "$ref" interpretation, exposing
inconsistent URI usage inside image-spec/schema.
So, this runs (vndr), and uses mtrmac/image-spec:id-based-loader
( https://github.com/opencontainers/image-spec/pull/739 ) to make the tests pass
again. As soon as that PR is merged we should revert to using the upstream
image-spec repo again.
