Fix test device_mesh-type-checking

Summary: Test [device_mesh-type-checking](https://www.internalfb.com/intern/test/562950220141718) was failing due to expecting type GroupName (an alias for str) while getting str. Make the manual conversion to make linter happy.

Reviewed By: siyengar

Differential Revision: D88663935

fbshipit-source-id: 1de27344d1eea830400ffea5f5599441eddff321

Author: YulunW

comms/torchcomms/device_mesh.py

@@ -9,6 +9,8 @@
 
 from torch.distributed.device_mesh import _mesh_resources
 
+from torch.distributed.distributed_c10d import GroupName
+
 from torchcomms._comms import _BackendWrapper, _get_store, new_comm, TorchComm
 
 
@@ -33,6 +35,10 @@ def _create_torchcomm_process_group(
     Returns:
         The created and registered ProcessGroup instance
     """
+    # Make the linter happy. GroupName is just an alias for str. The cost of
+    # this conversion is negligible.
+    group_name = GroupName(group_name)
+
     wrapper = _BackendWrapper(comm)  # noqa: F405
     backend_type = dist.ProcessGroup.BackendType.CUSTOM  # noqa: F841
     backend_config = dist.BackendConfig(dist.Backend(backend_str))