Patch release v4.47.1

We waited a little bit to make sure it was stable, thanks @winglian for double checking and everyone for the fixes!

• Fix GA loss bugs and add unit test (#35121) Contributed by @techkang and @ArthurZucker.

• Fix num_items_in_batch not being an integer (#35115) Contributed by @xspirus.

• Fix FSDP no longer working (#35212) Contributed by @muellerzr.

• Don't use no_sync when DeepSpeed doesn't support it for certain ZeRO configurations (#35212) Contributed by @winglian.

• Only import torch.distributed if it is available (#35133) Contributed by @GaetanLepage.

• [Whisper] Patch float type on MPS (#35295) Contributed by @eustlb. 🔜 we should probably have MPS CIs to avoid repeating this!