Fix torch.amp.autocast('cuda') warnings (#14633)

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Ultralytics Assistant <135830346+UltralyticsAssistant@users.noreply.github.com>

ultralytics/utils/checks.py

@@ -641,6 +641,8 @@ def check_amp(model):
     Returns:
         (bool): Returns True if the AMP functionality works correctly with YOLOv8 model, else False.
     """
+    from ultralytics.utils.torch_utils import autocast
+
     device = next(model.parameters()).device  # get model device
     if device.type in {"cpu", "mps"}:
         return False  # AMP only used on CUDA devices
@@ -648,7 +650,7 @@ def check_amp(model):
     def amp_allclose(m, im):
         """All close FP32 vs AMP results."""
         a = m(im, device=device, verbose=False)[0].boxes.data  # FP32 inference
-        with torch.cuda.amp.autocast(True):
+        with autocast(enabled=True):
             b = m(im, device=device, verbose=False)[0].boxes.data  # AMP inference
         del m
         return a.shape == b.shape and torch.allclose(a, b.float(), atol=0.5)  # close to 0.5 absolute tolerance