Format code with black

This commit fixes the style issues introduced in eae8f9c according to the output
from black.

Details: https://deepsource.io/gh/MilesCranmer/PySR/transform/b5aaa07e-e4fe-40a8-8945-54414bf75589/

test/test.py

@@ -149,9 +149,9 @@ class TestFeatureSelection(unittest.TestCase):
             np.sort(selected_X, axis=1), np.sort(X[:, [2, 3]], axis=1)
         )
 
-class TestHelperFunctions(unittest.TestCase):
 
-    @patch('builtins.input', side_effect=['y', 'n'])
+class TestHelperFunctions(unittest.TestCase):
+    @patch("builtins.input", side_effect=["y", "n"])
     def test_yesno(self, mock_input):
         # Assert that the yes/no function correctly deals with y/n
         self.assertEqual(_yesno("Test"), True)