ultralytics 8.0.43 optimized Results class and fixes (#1069)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Alexander Duda <Alexander.Duda@me.com>
Co-authored-by: Laughing <61612323+Laughing-q@users.noreply.github.com>

ultralytics/tracker/__init__.py

@@ -1,3 +1,4 @@
 # Ultralytics YOLO 🚀, GPL-3.0 license
 
+from .track import register_tracker
 from .trackers import BOTSORT, BYTETracker

ultralytics/tracker/track.py

@@ -1,13 +1,16 @@
 # Ultralytics YOLO 🚀, GPL-3.0 license
 
+from ultralytics.yolo.utils.checks import check_requirements, check_yaml
+
+check_requirements('lap')  # for linear_assignment
+
 import torch
 
-from ultralytics.tracker import BOTSORT, BYTETracker
 from ultralytics.yolo.utils import IterableSimpleNamespace, yaml_load
-from ultralytics.yolo.utils.checks import check_requirements, check_yaml
+
+from .trackers import BOTSORT, BYTETracker
 
 TRACKER_MAP = {'bytetrack': BYTETracker, 'botsort': BOTSORT}
-check_requirements('lap')  # for linear_assignment
 
 
 def on_predict_start(predictor):