Function deserialize 

pub fn deserialize<'de, Tz, D>(
    deserializer: D,
) -> Result<DateTime<Tz>, D::Error>
where
    Tz: TimeZone,
    DateTime<Tz>: From<DateTime<FixedOffset>>,
    D: Deserializer<'de>,

Deserializes a time field from an RFC 3339 string.