Skip test for MXNet version < 1.5.0 that crashes instead of throwing …

…exception.

Signed-off-by: Josh Romero <joshr@nvidia.com>

test/parallel/test_mxnet.py

@@ -487,6 +487,8 @@ def test_horovod_grouped_allreduce_inplace(self):
                 f'hvd.grouped_allreduce_ produces incorrect results: {hvd.rank()} {count} {dtype} {dim}'
 
     @unittest.skipUnless(has_gpu, "no gpu detected")
+    @pytest.mark.skipif(_skip_enqueue_errors,
+                        reason="Skip enqueue errors for MXNet version < 1.5.0")
     def test_horovod_grouped_allreduce_cpu_gpu_error(self):
         """Test that the grouped allreduce raises an error if the input tensor
            list contains a mix of tensors on CPU and GPU."""