use octokit gem to create a tag/release

There's a few options that could be used as well https://github.com/octokit/octokit.rb/blob/v3.5.2/lib/octokit/client/releases.rb#L19-L33

Specifically `name` and `body`. Also I wanted to use `prerelease` and set it to `!stage.production`, but release is not directly linked to a specific stage. Also not sure about `draft` key (defaults to false)