CI: Cover testing against linux-aarch64 + 2 GPUs

[leofang]

[leofang]

Hi @ajschmidt8 I noticed that the arm64 runner actually has 4 GPUs:
https://github.com/NVIDIA/cuda-python/actions/runs/12308859180/job/34356159459#step:5:30
Does it mean we can use it for multi-GPU tests (for which we have none today; this is for later development)?

[leofang]

Updated the title as the 1-GPU runner was added in #289. Spoke with AJ and the multi-GPU runner is currently blocked.

[cpcloud]

Happy to poke around here/ask the right people about multi-GPU runners.