remove deprecated args to learning rate step function (#890)

pytorch_lightning/trainer/training_loop.py

@@ -362,7 +362,7 @@ class TrainerTrainLoopMixin(ABC):
             # update LR schedulers
             if self.lr_schedulers is not None:
                 for lr_scheduler in self.lr_schedulers:
-                    lr_scheduler.step(epoch=self.current_epoch)
+                    lr_scheduler.step()
             if self.reduce_lr_on_plateau_scheduler is not None:
                 val_loss = self.callback_metrics.get('val_loss')
                 if val_loss is None:
@@ -370,7 +370,7 @@ class TrainerTrainLoopMixin(ABC):
                     m = f'ReduceLROnPlateau conditioned on metric val_loss ' \
                         f'which is not available. Available metrics are: {avail_metrics}'
                     raise MisconfigurationException(m)
-                self.reduce_lr_on_plateau_scheduler.step(val_loss, epoch=self.current_epoch)
+                self.reduce_lr_on_plateau_scheduler.step(val_loss)
 
             if self.max_steps and self.max_steps == self.global_step:
                 self.main_progress_bar.close()