ultralytics 8.0.136 refactor and simplify package (#3748)

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/utils/callbacks/raytune.py

@@ -0,0 +1,20 @@
+# Ultralytics YOLO 🚀, AGPL-3.0 license
+
+try:
+    import ray
+    from ray import tune
+    from ray.air import session
+except (ImportError, AssertionError):
+    tune = None
+
+
+def on_fit_epoch_end(trainer):
+    """Sends training metrics to Ray Tune at end of each epoch."""
+    if ray.tune.is_session_enabled():
+        metrics = trainer.metrics
+        metrics['epoch'] = trainer.epoch
+        session.report(metrics)
+
+
+callbacks = {
+    'on_fit_epoch_end': on_fit_epoch_end, } if tune else {}