Update deepspeed precision test (#12727)

Author: rohitgr7

tests/strategies/test_deepspeed_strategy.py

@@ -155,12 +155,13 @@ def test_deepspeed_strategy_env(tmpdir, monkeypatch, deepspeed_config):
 
 
 @RunIf(deepspeed=True)
+@mock.patch("torch.cuda.device_count", return_value=1)
 @pytest.mark.parametrize("precision", [16, "mixed"])
 @pytest.mark.parametrize(
     "amp_backend",
     ["native", pytest.param("apex", marks=RunIf(amp_apex=True))],
 )
-def test_deepspeed_precision_choice(amp_backend, precision, tmpdir):
+def test_deepspeed_precision_choice(_, amp_backend, precision, tmpdir):
     """Test to ensure precision plugin is also correctly chosen.
 
     DeepSpeed handles precision via Custom DeepSpeedPrecisionPlugin