fix(docker): Only build docker image on master or tag (#4644) r=vladikoff
fix(docker): Only build docker image on master or tag (#4644) r=vladikoff


mozilla/fxa-content-server,shane-tomlinson/fxa-content-server,mozilla/fxa-content-server,mozilla/fxa-content-server,shane-tomlinson/fxa-content-server,shane-tomlinson/fxa-content-server