cmd/coordinator: update Dockerfile

I plan to deploy the coordinator, so take this opportunity
to update it to the latest stable version of Go and Debian.

Change-Id: I59265478552fb5317be05fd517530c6deb2ef73d
Reviewed-on: https://go-review.googlesource.com/c/build/+/460035
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/cmd/coordinator/Dockerfile b/cmd/coordinator/Dockerfile
index e0dcf9c..53ece3e 100644
--- a/cmd/coordinator/Dockerfile
+++ b/cmd/coordinator/Dockerfile
@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
-FROM golang:1.17 AS build
+FROM golang:1.19 AS build
 LABEL maintainer="golang-dev@googlegroups.com"
 
 RUN mkdir /gocache
@@ -33,7 +33,7 @@
 RUN go install -ldflags "-X 'main.Version=$version'" golang.org/x/build/cmd/coordinator
 
 
-FROM debian:stretch AS build_drawterm
+FROM debian:bullseye AS build_drawterm
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     git-core ca-certificates make gcc libc6-dev libx11-dev
@@ -48,7 +48,7 @@
     rm -rf /tmp/conterm
 
 
-FROM debian:stretch
+FROM debian:bullseye
 
 # openssh client is for the gomote ssh proxy client.
 # telnet is for the gomote ssh proxy to windows. (no ssh server there)