Update vendor

vendor/github.com/google/go-containerregistry/pkg/crane/manifest.go

@@ -0,0 +1,32 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package crane
+
+// Manifest returns the manifest for the remote image or index ref.
+func Manifest(ref string, opt ...Option) ([]byte, error) {
+	desc, err := getManifest(ref, opt...)
+	if err != nil {
+		return nil, err
+	}
+	o := makeOptions(opt...)
+	if o.platform != nil {
+		img, err := desc.Image()
+		if err != nil {
+			return nil, err
+		}
+		return img.RawManifest()
+	}
+	return desc.Manifest, nil
+}