torchsnapshot nightlies / torch nightlies are broken on python < 3.10

[vmoens]

🐛 Describe the bug

As part of our CI we incorporate torchsnapshot nightlies tests.
Some signatures require python>3.9 as it appears here

The error reads

  File "/pytorch/rl/env/lib/python3.9/site-packages/torchsnapshot/io_preparers/sharded_tensor.py", line 200, in ShardedTensorIOPreparer
    ) -> Tuple[List[ReadReq], Future[ShardedTensor | torch.Tensor]]:
TypeError: unsupported operand type(s) for |: 'torch._C._TensorMeta' and 'torch._C._TensorMeta'

which occurs because https://github.com/pytorch/torchsnapshot/blob/main/torchsnapshot/io_preparers/sharded_tensor.py misses a

from __future__ import annotations

Versions

torch nightlies, python < 3.10