Follow FSDP name change (#1097)

`FSDP` -> `FSDPModule`

pippy/PipelineStage.py

@@ -8,7 +8,7 @@
 import torch.distributed as dist
 import torch.fx as fx
 from torch._subclasses.fake_tensor import FakeTensor
-from torch.distributed._composable.fsdp.fully_shard import FSDP
+from torch.distributed._composable.fsdp.fully_shard import FSDPModule
 from torch.fx.node import map_aggregate
 from torch.nn.parallel import DistributedDataParallel
 
@@ -367,7 +367,7 @@ def _configure_data_parallel_mode(self, last_backward: bool):
         there are additional state-variables and performance considerations depending on the data parallelism used.
         This helper should adapt any pipeline parallel schedule to work with common/supported data parallel libraries.
         """
-        if isinstance(self.submod, FSDP):
+        if isinstance(self.submod, FSDPModule):
             self.submod.set_is_last_backward(last_backward)
             self.submod.set_requires_gradient_sync(last_backward)