TimetrackingsTrackingRecord not implemented correctly

[JanHolger]

Hi,
first of all thank you for building this amazing client. While trying to create a timesheet I faced the following issue.

Currently TimetrackingsTrackingRecord is implemented like this:

interface TimetrackingsTrackingRecord {
    type: "duration" | "range";
    date: string;
    duration: string;
}

but this only allows for the duration type.

There are 2 ways to approach this issue

1. Implement 2 interfaces and use a union type

interface TimetrackingsTrackingDurationRecord {
    type: "duration";
    date: string;
    duration: string;
}
interface TimetrackingsTrackingRangeRecord {
    type: "range";
    start: string;
    end: string;
}

interface TimetrackingsCreate {
    ...
    tracking: TimetrackingsTrackingDurationRecord | TimetrackingsTrackingRangeRecord;
    ...
}

2. Make duration and date optional and also add the start and end properties as optional

interface TimetrackingsTrackingRecord {
    type: "duration" | "range";
    date: string;
    duration?: string;
    start?: string;
    end?: string;
}

[mathewmeconry]

Hey
I would go with option 1 so we have proper the correct fields with the type.
I am open for pull requests because I probably won't be able to update the lib in the next 3 weeks :(