chrono ser/de

time.rs

```

#[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Serialize, Deserialize, Hash)]
pub struct Time {
    // utc timestamp
    timestamp: i64,
    // timezone offset
    offset: i32,
}

impl<T> From<DateTime<T>> for Time
where
    T: TimeZone,
{
    fn from(date_time: DateTime<T>) -> Self {
        let timestamp = date_time.timestamp();
        let offset = date_time.offset().fix().local_minus_utc();
        Time { timestamp, offset }
    }
}

impl<'a> Into<DateTime<FixedOffset>> for &'a Time {
    fn into(self) -> DateTime<FixedOffset> {
        DateTime::from_utc(
            NaiveDateTime::from_timestamp(self.timestamp(), 0),
            FixedOffset::east(self.offset()),
        )
    }
}
```