[Fix] Fix warning capture (#1494)

tests/test_utils/test_dl_utils/test_torch_ops.py

@@ -1,5 +1,6 @@
 # Copyright (c) OpenMMLab. All rights reserved.
-import pytest
+import warnings
+
 import torch
 
 from mmengine.utils.dl_utils import torch_meshgrid
@@ -7,9 +8,8 @@ from mmengine.utils.dl_utils import torch_meshgrid
 
 def test_torch_meshgrid():
     # torch_meshgrid should not throw warning
-    with pytest.warns(None) as record:
+    with warnings.catch_warnings():
+        warnings.simplefilter('error')
         x = torch.tensor([1, 2, 3])
         y = torch.tensor([4, 5, 6])
         grid_x, grid_y = torch_meshgrid(x, y)
-
-    assert len(record) == 0