Currently CI builds container images when pushing to the
feat/standalone_snark_worker or to a PR targeted to that branch.
Images are available at the Docker Hub repository openmina/openmina.
For the branch itself, two tags produced, one derived from the commit hash
(first 8 chars), and another one is latest.
For a PR from a branch named some/branch, two tags are produced, one is some-branch-<commit-hash> and another one is some-branch-latest.