Update vendor

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

@@ -0,0 +1,37 @@
+// 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
+
+import (
+	"fmt"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/google/go-containerregistry/pkg/v1/tarball"
+)
+
+// Append reads a layer from path and appends it the the v1.Image base.
+func Append(base v1.Image, paths ...string) (v1.Image, error) {
+	layers := make([]v1.Layer, 0, len(paths))
+	for _, path := range paths {
+		layer, err := tarball.LayerFromFile(path)
+		if err != nil {
+			return nil, fmt.Errorf("reading tar %q: %v", path, err)
+		}
+		layers = append(layers, layer)
+	}
+
+	return mutate.AppendLayers(base, layers...)
+}