[FEA]: Setup CI job to automate testing with CuPy

### Is this a duplicate?

- [X] I confirmed there appear to be no [duplicate issues](https://github.com/NVIDIA/cccl/issues) for this request and that I agree to the [Code of Conduct](CODE_OF_CONDUCT.md)

### Area

Infrastructure

### Is your feature request related to a problem? Please describe.

As a CCCL maintainer, I want to be sure we aren't breaking important users like [`CuPy`](https://github.com/NVIDIA/cccl/issues/1493) that effectively exposes Thrust and CUB to Python.

However, we've had several breakages in just the last few months, e.g., https://github.com/NVIDIA/cccl/issues/1493

### Describe the solution you'd like

We should setup either a nightly or per-PR CI job that runs the CuPy build against the latest CCCL code to make sure we're catching things that break.

### Describe alternatives you've considered

_No response_

### Additional context

_No response_