release prep: push docker image upon tagging (#325)
release prep: push docker image upon tagging (#325)

Signed-off-by: Otto van der Schaaf <f82e1104fcd8bfffc72e7185709f7902b0b97ebf@we-amp.com>
envoyproxy/nighthawk,envoyproxy/nighthawk,envoyproxy/nighthawk,envoyproxy/nighthawk