Update docker_main.yml to run in PRs against release branches#8

EnriqueL8 wants to merge 1 commit intorelease-0.9.21kaleido-io/firefly-fabconnect:release-0.9.21from

EnriqueL8-patch-2kaleido-io/firefly-fabconnect:EnriqueL8-patch-2Copy head branch name to clipboard