* Reverts the recent 'torch.mps' changes since .mps is only available in torch v2.0, which isn't yet released.
* Includes Hotfitx 984
* Enables 'cpu-only' option when running on Apple silicon.
Changes:
* autodetect if MPS is available and the pytorch version has MPS support.
* change logic from "is the device CPU?" to "is the device not CUDA?".
* set PYTORCH_ENABLE_MPS_FALLBACK=1
Known issues:
* Some samplers (eg DDIM) will fail on MPS unless forced to CPU-only mode