message: Remove now-unnecessary merge layer error test
diff: @@ -287,8 +287,6 @@ class MergeLayersTestNoExecution(test.TestCase):
  keras.layers.concatenate([i1, i2], axis=-1)
  with self.assertRaisesRegex(ValueError, 'called on a list'):
  keras.layers.concatenate(i1, axis=-1)
  - with self.assertRaisesRegex(ValueError, 'called on a list'):
  - keras.layers.concatenate([i1], axis=-1)
  def test_concatenate_with_partial_shape(self):
  i1 = keras.layers.Input(shape=(5,), batch_size=32)
  