Ultralytics Asset URL Update (#13181)

Refactor code for speed and clarity

classify/train.py

@@ -109,7 +109,7 @@ def train(opt, device):
             if str(data) == "imagenet":
                 subprocess.run(["bash", str(ROOT / "data/scripts/get_imagenet.sh")], shell=True, check=True)
             else:
-                url = f"https://github.com/ultralytics/yolov5/releases/download/v1.0/{data}.zip"
+                url = f"https://github.com/ultralytics/assets/releases/download/v0.0.0/{data}.zip"
                 download(url, dir=data_dir.parent)
             s = f"Dataset download success ✅ ({time.time() - t:.1f}s), saved to {colorstr('bold', data_dir)}\n"
             LOGGER.info(s)