Migrate to containerd 1.54

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/google.golang.org/grpc/internal/grpcutil/metadata.go

@@ -0,0 +1,40 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * 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 grpcutil
+
+import (
+	"context"
+
+	"google.golang.org/grpc/metadata"
+)
+
+type mdExtraKey struct{}
+
+// WithExtraMetadata creates a new context with incoming md attached.
+func WithExtraMetadata(ctx context.Context, md metadata.MD) context.Context {
+	return context.WithValue(ctx, mdExtraKey{}, md)
+}
+
+// ExtraMetadata returns the incoming metadata in ctx if it exists.  The
+// returned MD should not be modified. Writing to it may cause races.
+// Modification should be made to copies of the returned MD.
+func ExtraMetadata(ctx context.Context) (md metadata.MD, ok bool) {
+	md, ok = ctx.Value(mdExtraKey{}).(metadata.MD)
+	return
+}