Fix/format colossalai/engine/paramhooks/(#350)

colossalai/engine/paramhooks/__init__.py

@@ -1,2 +1,3 @@
 from ._param_hookmgr import BaseParamHookMgr
+
 __all__ = ["BaseParamHookMgr"]

colossalai/engine/paramhooks/_param_hookmgr.py

@@ -2,7 +2,9 @@ from typing import Callable, List
 import torch
 import functools
 
+
 class BaseParamHookMgr(object):
+
     def __init__(self, param_list: List[torch.nn.Parameter]) -> None:
         r"""
         register backward hook on every parameters of module