Support print build date and version

[zheng1]

If there is a docker mirror cache, printing out the build date and version is good for debugging

tower/.github/workflows/go.yml

Lines 56 to 57 in 786fdd1

	--build-arg BUILD_DATE=$(date -u +'%Y-%m-%dT%H:%M:%SZ') \
	--build-arg VCS_REF=${GITHUB_SHA::8} \