use union instead of | (#358)

python/tests/mlx_tests.py

@@ -2,7 +2,7 @@
 
 import os
 import unittest
-from typing import Any, Callable, List, Tuple
+from typing import Any, Callable, List, Tuple, Union
 
 import mlx.core as mx
 import numpy as np
@@ -21,7 +21,7 @@ class MLXTestCase(unittest.TestCase):
 
     def assertCmpNumpy(
         self,
-        shape: List[Tuple[int] | Any],
+        shape: List[Union[Tuple[int], Any]],
         mx_fn: Callable[..., mx.array],
         np_fn: Callable[..., np.array],
         atol=1e-2,