This commit migrates the project from using NVIDIA CUDA to Intel XPU for GPU acceleration, based on the PyTorch 2.9 release.
Key changes include:
- Replaced `torch.cuda` with `torch.xpu` for device checks, memory management, and distributed training.
- Updated device strings from "cuda" to "xpu" across the codebase.
- Switched the distributed training backend from "nccl" to "ccl" for Intel GPUs.
- Disabled custom CUDA kernels in the `BigVGAN` module by setting `use_cuda_kernel=False`.
- Updated `requirements.txt` to include `torch==2.9` and `intel-extension-for-pytorch`.
- Modified CI/CD pipelines and build scripts to remove CUDA dependencies and build for an XPU target.
