Switch tests to use latest etcd - 3.1.3

Let's move on to newer releases of etcd. Especially since
3.1.x introduced some backwards incompatible changes

https://github.com/coreos/etcd/releases

Change-Id: I3887dbb745fb6de844c4b60d43b6543f441f239b

setup-etcd-env.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 set -eux
 if [ -z "$(which etcd)" ]; then
-    ETCD_VERSION=3.0.6
+    ETCD_VERSION=3.1.3
     case `uname -s` in
         Darwin)
             OS=darwin