In order to make sure that we don't create invalid OCI images that are
consistently invalid, add additional checks to ensure that both of the
generated OCI images in the round-trip test are valid according to the
upstream validator.
This commit vendors the following packages (deep breath):
* oci/image-tools@7575a09363, which requires
* oci/image-spec@v1.0.0-rc4 [revendor, but is technically an update
because I couldn't figure out what version was vendored last time]
* oci/runtime-spec@v1.0.0-rc4
* xeipuuv/gojsonschema@6b67b3fab7
* xeipuuv/gojsonreference@e02fc20de9
* xeipuuv/gojsonpointer@e0fe6f6830
* camlistore/go4@7ce08ca145
Signed-off-by: Aleksa Sarai <asarai@suse.de>
