style: ensure trailing newlines

tests/unit/utils/test_assert_that_is_instance.py

@@ -40,4 +40,4 @@ def test_assert_that_is_instance(obj, class_or_tuple):
 def test_assert_that_is_instance_exceptions(obj, class_or_tuple, expected_exception_msg):
     with pytest.raises(TypeError) as exc_info:
         assert_that_is_instance(obj, class_or_tuple)
-    assert str(exc_info.value) == expected_exception_msg
+    assert str(exc_info.value) == expected_exception_msg