ContainerRegistry: Pass through the manifest's mediaType, if set

Sources/ContainerRegistry/Manifests.swift

@@ -14,14 +14,15 @@
 
 public extension RegistryClient {
  func putManifest(repository: String, reference: String, manifest: ImageManifest) async throws -> String {
+ // See https://github.com/opencontainers/distribution-spec/blob/main/spec.md#pushing-manifests
  precondition(repository.count > 0, "repository must not be an empty string")
  precondition(reference.count > 0, "reference must not be an empty string")
 
  let httpResponse = try await executeRequestThrowing(
  // All blob uploads have Content-Type: application/octet-stream on the wire, even if mediatype is different
  .put(
  registryURLForPath("/v2/\(repository)/manifests/\(reference)"),
- contentType: "application/vnd.oci.image.manifest.v1+json"
+ contentType: manifest.mediaType ?? "application/vnd.oci.image.manifest.v1+json"
  ),
  uploading: manifest,
  expectingStatus: .created,
@@ -35,6 +36,7 @@ public extension RegistryClient {
  }
 
  func getManifest(repository: String, reference: String) async throws -> ImageManifest {
+ // See https://github.com/opencontainers/distribution-spec/blob/main/spec.md#pulling-manifests
  precondition(repository.count > 0, "repository must not be an empty string")
  precondition(reference.count > 0, "reference must not be an empty string")