Rename validation_epoch_end -> on_validation_epoch_end

ref Lightning-AI/pytorch-lightning#16520

Author: ddelange

multimodal/src/autogluon/multimodal/optimization/lit_mmdet.py

@@ -230,7 +230,7 @@ def validation_step(self, batch, batch_idx, dataloader_idx=0):
         else:
             self.evaluate(batch, "val")
 
-    def validation_epoch_end(self, validation_step_outputs):
+    def on_validation_epoch_end(self):
         val_result = self.validation_metric.compute()
         if self.use_loss:
             self.log_dict({"val_direct_loss": val_result}, sync_dist=True)