fix LegacyKeyValueFormat warnings

> LegacyKeyValueFormat: "LABEL key=value" should be used instead of legacy "LABEL key value"
> LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value"

create_dockerfile.sh

@@ -41,13 +41,13 @@ create_dockerfile() {
   cat >"${DOCKERFILE}" <<EOF
 FROM ${docker_tag}
 
-LABEL org.opencontainers.image.authors Victor Seva <[email protected]>
+LABEL org.opencontainers.image.authors="Victor Seva <[email protected]>"
 
 # Important! Update this no-op ENV variable when this Dockerfile
 # is updated with the current date. It will force refresh of all
 # of the base images and things like 'apt-get update' won't be using
 # old cached versions when the Dockerfile is built.
-ENV REFRESHED_AT ${DATE}
+ENV REFRESHED_AT=${DATE}
 EOF
 
 if ${archived} ; then