fix with statement in test_fsdp_hybrid_shard.py (#90580)
Fixes PR #89915. The following syntax was not permitted until 3.10:
```
with (
patch_allreduce(patched_allreduce),
patch_reduce_scatter(patched_reduce_scatter),
):
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/90580
Approved by: https://github.com/awgu
