test(cufile): drop useless yield from prewarm fixture

The _cufile_driver_prewarm fixture has no teardown — the open/close cycle
is setup-only. Keeping a trailing `yield` made ruff's PT022
(pytest-useless-yield-fixture) flag it. Drop the yield so the fixture runs
as pure setup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: cpcloud

cuda_bindings/tests/test_cufile.py

@@ -183,7 +183,6 @@ def _cufile_driver_prewarm():
         cufile.driver_close()
     finally:
         cuda.cuDevicePrimaryCtxRelease(device)
-    yield
 
 
 @pytest.fixture