ultralytics 8.0.188 fix .grad attribute leaf Tensor Warning (#5094)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

ultralytics/engine/validator.py

@@ -95,6 +95,7 @@ class BaseValidator:
         (self.save_dir / 'labels' if self.args.save_txt else self.save_dir).mkdir(parents=True, exist_ok=True)
         if self.args.conf is None:
             self.args.conf = 0.001  # default conf=0.001
+        self.args.imgsz = check_imgsz(self.args.imgsz, max_dim=1)
 
         self.plots = {}
         self.callbacks = _callbacks or callbacks.get_default_callbacks()