Selection of fixes

• Protecting the imports for SigLIP's tokenizer if sentencepiece isn't installed
• Fix permissions issue on windows machines when using trainer in multi-node setup
• Allow disabling safe serialization when using Trainer. Needed for Neuron SDK
• Fix error when loading processor from cache
• torch < 1.13 compatible torch.load

Commits

• [Siglip] protect from imports if sentencepiece not installed (#28737)
• Fix weights_only (#28725)
• Enable safetensors conversion from PyTorch to other frameworks without the torch requirement (#27599)
• Don't fail when LocalEntryNotFoundError during processor_config.json loading (#28709)
• Use save_safetensor to disable safe serialization for XLA (#28669)
• Fix windows err with checkpoint race conditions (#28637)
• [SigLIP] Only import tokenizer if sentencepiece available (#28636)