Apply ruff lint suggestion - combine nested if statements

Co-authored-by: Borda <[email protected]>

Author: Copilot

src/lightning/pytorch/loops/fit_loop.py

@@ -481,12 +481,15 @@ def on_advance_end(self) -> None:
 
         trainer._logger_connector.on_epoch_end()
 
-        if not self.restarting and self.epoch_loop._num_ready_batches_reached():
-            # since metric-based schedulers require access to metrics and those are not currently saved in the
-            # checkpoint, the plateau schedulers shouldn't be updated when restarting
-            # only update plateau schedulers if validation ran this epoch to ensure monitored metrics are available
-            if self.epoch_loop._should_check_val_epoch():
-                self.epoch_loop.update_lr_schedulers("epoch", update_plateau_schedulers=True)
+        # since metric-based schedulers require access to metrics and those are not currently saved in the
+        # checkpoint, the plateau schedulers shouldn't be updated when restarting
+        # only update plateau schedulers if validation ran this epoch to ensure monitored metrics are available
+        if (
+            not self.restarting
+            and self.epoch_loop._num_ready_batches_reached()
+            and self.epoch_loop._should_check_val_epoch()
+        ):
+            self.epoch_loop.update_lr_schedulers("epoch", update_plateau_schedulers=True)
 
         # we manually decrease here because loggers expect that the same step is used when logging epoch-end metrics
         # even when the batch loop has finished