Publish a `stable` release channel which tracks the latest stable release

[danielsn]

Requested feature: What it says in the title
Use case: Users may wish to get the latest and greatest kani without needing to manually update after each release.

[YoshikiTakashima]

Reposting from PROST discussion: This could be implemented by running https://github.com/marketplace/actions/latest-tag at every release.