Import `ultralytics.nn.tasks` as `ultralytics.nn` (#2889)

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

ultralytics/nn/__init__.py

@@ -0,0 +1,9 @@
+# Ultralytics YOLO 🚀, AGPL-3.0 license
+
+from .tasks import (BaseModel, ClassificationModel, DetectionModel, SegmentationModel, attempt_load_one_weight,
+                    attempt_load_weights, guess_model_scale, guess_model_task, parse_model, torch_safe_load,
+                    yaml_model_load)
+
+__all__ = ('attempt_load_one_weight', 'attempt_load_weights', 'parse_model', 'yaml_model_load', 'guess_model_task',
+           'guess_model_scale', 'torch_safe_load', 'DetectionModel', 'SegmentationModel', 'ClassificationModel',
+           'BaseModel')