Change strict_load of EMAHook to False by default (#642)

* [Fix] resume std and mean

* refine docstring

Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

mmengine/hooks/ema_hook.py

@@ -27,11 +27,12 @@ class EMAHook(Hook):
             Defaults to 'ExponentialMovingAverage'.
         strict_load (bool): Whether to strictly enforce that the keys of
             ``state_dict`` in checkpoint match the keys returned by
-            ``self.module.state_dict``. Defaults to True.
+            ``self.module.state_dict``. Defaults to False.
+            Changed in v0.3.0.
         begin_iter (int): The number of iteration to enable ``EMAHook``.
             Defaults to 0.
-        begin_epoch (int): The number of epoch to enable ``EMAHook``. Defaults
-            to 0.
+        begin_epoch (int): The number of epoch to enable ``EMAHook``.
+            Defaults to 0.
         **kwargs: Keyword arguments passed to subclasses of
             :obj:`BaseAveragedModel`
     """
@@ -40,7 +41,7 @@ class EMAHook(Hook):
 
     def __init__(self,
                  ema_type: str = 'ExponentialMovingAverage',
-                 strict_load: bool = True,
+                 strict_load: bool = False,
                  begin_iter: int = 0,
                  begin_epoch: int = 0,
                  **kwargs):