GPU CI

[martinfleis]

As of 0.7.0, we have the test coverage at 99% but on GHA, we are only able to get to ~80% since the rest requires the rapids.ai stack running on GPU. I can test locally now, thanks to the machine at the university but I'll likely lose access to that one at some point.

It would be ideal to be able to run CI on every PR automatically on GPU but I am not aware of any option that is not charging for that. Opening the post to keep an eye on something.