Set up release and version numbering in CI

[supakeen]

We have a spec file since #66, let's also set up our release and version numbering.

Do we want to do the same release scheduling ideas as the rest of our projects or do we want to opt for a different setup in otk?

[bcl]

Initially I think releasing quickly is important, assuming there will be users beta testing it. As it gets more stable we can switch to regular release schedules.
I'd also like to see it emphasize unit tests that can be run locally (ideally as part of a git hook) instead of heavy CI depending on outside resources that are always broken.
And I really like the github merge queue, I'm not sure how to set that up but @achilleas-k does. The way it works with the images repo is really nice.

[supakeen]

We already have the merge queue enabled in this repository and the goal of keeping our unit tests small and possible to run locally in pre-commit is something I love too; @schuellerf already did some work on setting it up.