ultralytics 8.0.18 new python callbacks and minor fixes (#580)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Jeroen Rombouts <36196499+jarombouts@users.noreply.github.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

ultralytics/yolo/v8/detect/val.py

@@ -20,6 +20,7 @@ class DetectionValidator(BaseValidator):
 
     def __init__(self, dataloader=None, save_dir=None, pbar=None, logger=None, args=None):
         super().__init__(dataloader, save_dir, pbar, logger, args)
+        self.args.task = 'detect'
         self.data_dict = yaml_load(check_file(self.args.data), append_filename=True) if self.args.data else None
         self.is_coco = False
         self.class_map = None