Move to release automation

!7 (merged) freshened the CI configuration for this library but we can't move to release automation because there isn't a GitLab token configured. This is, in turn, because this group (and others like uis/devops/lib) use the "shared code" Google project and GitLab project factory currently does not support multiple products sharing the same Google infrastructure. See https://gitlab.developers.cam.ac.uk/uis/devops/infra/gitlab-project-factory/-/issues/43.