vendor: update all dependencies

vendor/golang.org/x/net/http2/h2demo/Dockerfile

@@ -0,0 +1,11 @@
+# Copyright 2018 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+FROM scratch
+LABEL maintainer "golang-dev@googlegroups.com"
+
+COPY ca-certificates.crt /etc/ssl/certs/
+COPY h2demo /
+ENTRYPOINT ["/h2demo", "-prod"]
+