remove custom transport

Signed-off-by: Meredith Lancaster <malancas@github.com>

pkg/cmd/attestation/artifact/oci/client.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"net/http"
 	"strings"
 
 	"github.com/google/go-containerregistry/pkg/authn"
@@ -69,33 +68,10 @@ func (c LiveClient) GetImageDigest(imgName string) (*v1.Hash, name.Reference, er
 	return &desc.Digest, name, nil
 }
 
-type noncompliantRegistryTransport struct{}
-
-// RoundTrip will check if a request and associated response fulfill the following:
-// 1. The response returns a 406 status code
-// 2. The request path contains /referrers/
-// If both conditions are met, the response's status code will be overwritten to 404
-// This is a temporary solution to handle non compliant registries that return
-// an unexpected status code 406 when the go-containerregistry library used
-// by this code attempts to make a request to the referrers API.
-// The go-containerregistry library can handle 404 response but not a 406 response.
-// See the related go-containerregistry issue: https://github.com/google/go-containerregistry/issues/1962
-func (a *noncompliantRegistryTransport) RoundTrip(req *http.Request) (*http.Response, error) {
-	resp, err := http.DefaultTransport.RoundTrip(req)
-	if err != nil {
-		return resp, err
-	}
-	if resp.StatusCode == http.StatusNotAcceptable && strings.Contains(req.URL.Path, "/referrers/") {
-		resp.StatusCode = http.StatusNotFound
-	}
-
-	return resp, err
-}
-
 func (c LiveClient) GetAttestations(ref name.Reference, digest string) ([]*api.Attestation, error) {
 	attestations := make([]*api.Attestation, 0)
 
-	transportOpts := []remote.Option{remote.WithTransport(&noncompliantRegistryTransport{}), remote.WithAuthFromKeychain(authn.DefaultKeychain)}
+	transportOpts := []remote.Option{remote.WithAuthFromKeychain(authn.DefaultKeychain)}
 	referrers, err := remote.Referrers(ref.Context().Digest(digest), transportOpts...)
 	if err != nil {
 		return attestations, fmt.Errorf("error getting referrers: %w", err)