[FSDP][Easy] ufmt `test_fsdp_checkpoint.py` (#89916)
I am in the habit now to run `ufmt format test/distributed/fsdp` before committing, and this changed `test_fsdp_checkpoint.py`. I separated this into its own PR. This change should be safe to force merge to save CI.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/89916
Approved by: https://github.com/mrshenli
