Update vendor

vendor/github.com/google/go-containerregistry/pkg/logs/logs.go

@@ -0,0 +1,39 @@
+// 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 logs exposes the loggers used by this library.
+package logs
+
+import (
+	"io/ioutil"
+	"log"
+)
+
+var (
+	// Warn is used to log non-fatal errors.
+	Warn = log.New(ioutil.Discard, "", log.LstdFlags)
+
+	// Progress is used to log notable, successful events.
+	Progress = log.New(ioutil.Discard, "", log.LstdFlags)
+
+	// Debug is used to log information that is useful for debugging.
+	Debug = log.New(ioutil.Discard, "", log.LstdFlags)
+)
+
+// Enabled checks to see if the logger's writer is set to something other
+// than ioutil.Discard. This allows callers to avoid expensive operations
+// that will end up in /dev/null anyway.
+func Enabled(l *log.Logger) bool {
+	return l.Writer() != ioutil.Discard
+}