Add GitHub Action to bump homebrew cask

[dannysteenman]

I think now the homebrew cask is updated manually?

There's an option to automatically bump the homebrew cask version using this github action from the marketplace:

https://github.com/marketplace/actions/homebrew-bump-cask

[idan]

I think the homebrew cask is going to need to get updated given that the underlying packages are now different. Also maybe there will be more than one cask or some options depending on which variant of monaspace you desire?

As a longtime user of homebrew, I have no idea how it works inside, if anyone wants to help out with this, would be appreciated!

[injust]

Homebrew's livecheck usually handles the auto-bump. But with v1.3 changing the release format, this is being done manually in https://github.com/Homebrew/homebrew-cask/pull/224797.