[NFC] polish communication/p2p_v2.py code style (#2303)

colossalai/communication/p2p_v2.py

@@ -1,14 +1,14 @@
 #!/usr/bin/env python
 # -*- encoding: utf-8 -*-
 
-from typing import List, Tuple, Union, Any
-import pickle
 import io
+import pickle
+from typing import Any, List, Tuple, Union
 
 import torch
 import torch.distributed as dist
-from torch.distributed import distributed_c10d as c10d
 from torch.distributed import ProcessGroupNCCL
+from torch.distributed import distributed_c10d as c10d
 
 from colossalai.context.parallel_mode import ParallelMode
 from colossalai.core import global_context as gpc