serializeMsgpack incorrectly serializes Duration

[Labuurii]

serializeMsgpack incorrectly serializes Duration and causes deserializeMsgpack to fail.

import mir.deser.msgpack;
import mir.ser.msgpack;
import std.datetime;

void main()
{
	static struct D {
		Duration d;
	}
	
	auto d = D(dur!"minutes"(1));
	d.serializeMsgpack
		.deserializeMsgpack!D; // Throws exception
}

With error msg:
source\mir\timestamp.d(34): Timestamp: Expected Duration