Support non-standard "application/vnd.docker.image.rootfs.diff.tar.zstd" layer type used by BuildKit

[zhill]

What happened:
Stereoscope, via Syft, rejects the content of a public docker image built with latest BuildKit via the official Docker GHA.

syft registry:docker.io/rapidsai/base:25.12a-cuda12-py3.10 -v   
[0000]  INFO syft version: 1.38.0
[0001]  INFO completed downloading image from=stereoscope image=docker.io/rapidsai/base:25.12a-cuda12-py3.10 time=1.322479459s
[0001] ERROR could not determine source: an error occurred attempting to resolve 'docker.io/rapidsai/base:25.12a-cuda12-py3.10': oci-registry: unknown layer media type: application/vnd.docker.image.rootfs.diff.tar.zstd

What you expected to happen:

It should pull and analyze the image correctly.

How to reproduce it (as minimally and precisely as possible):
docker.io/rapidsai/base:25.12a-cuda12-py3.10

crane manifest docker.io/rapidsai/base:25.12a-cuda12-py3.10       
{
   "schemaVersion": 2,
   "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
   "manifests": [
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "size": 4427,
         "digest": "sha256:1631bfda7914218c71e2463a41591a64f0616ff0f09f530ddf80caf794bdc1b1",
         "platform": {
            "architecture": "amd64",
            "os": "linux"
         }
      },
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "size": 4427,
         "digest": "sha256:dbba980d26853ab1fc3db1fec4e9703941fadfb7c8cbcc6682c69198c094096d",
         "platform": {
            "architecture": "arm64",
            "os": "linux"
         }
      }
   ]
}%

Anything else we need to know?:
Even though it isn't expected as a mediaType due to the '.zstd' instead of the expected '+zstd', Crane, Skopeo and Docker Daemon will pull the image just fine, so it should be supported in Stereoscope.

Environment:

• OS (e.g: cat /etc/os-release or similar):
  MacOS and Linux, on both amd64 and arm64. This does not appear to be relevant to this issue however.