gitlab container registry would need to support Flux media types

We get this error when using Flux to push an OCI registry artifact to a container registry under registry.gitlab.com:

flux push artifact oci://registry.gitlab.com/sylva-projects/sylva-core/kustomize-units:test --path=. --source=git@gitlab.com:sylva-projects/sylva-core.git --revision=kustomize-units-oci-artifact/0574980c2e57149cb5879c27c61cba2551040e59                 
► pushing artifact to registry.gitlab.com/sylva-projects/sylva-core/kustomize-units:tmorin-test
✗ pushing artifact failed: pushing artifact failed: PUT https://registry.gitlab.com/v2/sylva-projects/sylva-core/kustomize-units/manifests/tmorin-test: MANIFEST_INVALID: manifest invalid; unknown media type: application/vnd.cncf.flux.config.v1+json

Flux CD maintainer Stefan Prodan explained that gitlab.com registry could possibly be configured to accept some media types that are used by Flux:

Starting with Flux 0.40 the artifacts produced by the CLI are proper OCI artifacts and looks like GitLab doesn't support that.

The OCI artifacts produced with flux push artifact have the following media types:

• artifact media type application/vnd.oci.image.manifest.v1+json
• config media type application/vnd.cncf.flux.config.v1+json
• content media type application/vnd.cncf.flux.content.v1.tar+gzip Please open an issue with them, they should be able to add vnd.cncf.flux to their allow list.