fix cyclic import

Author: awaelchli

pytorch_lightning/overrides/base.py

@@ -15,7 +15,7 @@
 
 import torch
 
-from pytorch_lightning import LightningModule
+from pytorch_lightning.core.lightning import LightningModule
 from pytorch_lightning.trainer.states import RunningStage
 from pytorch_lightning.utilities.warnings import WarningCache
 

pytorch_lightning/overrides/distributed.py

@@ -17,7 +17,7 @@
 import torch
 from torch.nn.parallel import DistributedDataParallel
 
-from pytorch_lightning import LightningModule
+from pytorch_lightning.core.lightning import LightningModule
 from pytorch_lightning.overrides.base import _LightningModuleWrapperBase