Cast to timestamp with time zone returns timestamp

[comphead]

Describe the bug

Cast to timestamp with time zone returns timestamp

To Reproduce

    #[test]
    fn test_cast_utf8_to_timestamptz() {
            let valid = StringArray::from(vec![
                "2023-01-01",
            ]);

            let array = Arc::new(valid) as ArrayRef;
            let b = cast(&array, &DataType::Timestamp(TimeUnit::Nanosecond, Some("+00:00".to_owned())))
                .unwrap();

            dbg!(&b);

    }

[arrow-cast/src/cast.rs:7653] &b = PrimitiveArray<Timestamp(Nanosecond, None)>
[
  2023-01-01T00:00:00,
]

Expected behavior

The return type has to be

PrimitiveArray<Timestamp(Nanosecond, Some("+00:00"))>

Additional context

[comphead]

Probably related to #1936

[tustvold]

label_issue.py automatically added labels {'arrow'} from #3806