Support of unsigned integers `u64`

[GeorgFritze]

As far as I understand this library do not yet support unsigned integers (uint64).
FieldValue – data_point.rs#L147

/// Possible value types
#[derive(Debug, Clone, PartialEq)]
pub enum FieldValue {
    /// A true or false value
    Bool(bool),
    /// A 64-bit floating point number
    F64(f64),
    /// A 64-bit signed integer number
    I64(i64),
    /// A string value
    String(String),
}

Is there a plan to support uint64 as specified in the line protocol documentation. Line protocol

myMeasurement fieldKey=1u
myMeasurement fieldKey=12485903u