CI: Automate release

[zeppelin]

• Updates ci.yaml to make tests running on maintenance branches
• Adds release.yml action config
• Mirror release-it config with ember-prismic-dom

[mrloop]

@zeppelin I'd like to make a release and it'd be great if I could use release-it. Have you any time to update this PR?

[zeppelin]

@mrloop I can rebase today, if that's what you mean

[mrloop]

Thanks! Tried running yarn release-it --dry-run locally and looks OK. NPM_TOKEN now setup for this repo, going to wait till Monday morning to try first release-it release out of abundance of caution it being late on a Friday.

[mrloop]

Running yarn locally and yarn.lock is updated. Think you need to push update yarn.lock @zeppelin

[zeppelin]

Updated! Hope it's good now, yarn does odd things sometimes...