ultralytics 8.1.44 add IS_RASPBERRYPI and constants refactor (#9827)

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>

ultralytics/engine/trainer.py

@@ -464,6 +464,7 @@ class BaseTrainer:
     def save_model(self):
         """Save model training checkpoints with additional metadata."""
         import io
+
         import pandas as pd  # scope for faster 'import ultralytics'
 
         # Serialize ckpt to a byte buffer once (faster than repeated torch.save() calls)