`TimeRange` CustomField isn't parsed properly

[paw-eloquent-safe]

Describe the bug When handling a PipeDrive response with a TimeRange Custom Field. The function CustomFieldConverter.ReadJson() throws an exception since it tries to parse an time span represented as an string as an integer.

To Reproduce Steps to reproduce the behavior:

1. Add a custom TimeRange field to your deal.
2. Create a deal.
3. Mutate/edit/update the deal using PipedriveApiClient.Deal.Edit(), while making sure to set the custom TimeRange field you just created.
4. Wait for the response to be recieved/parsed.
5. Error while deserializing.

Expected behavior I expected pipedrive-dotnet to parse this as an timespan not an integer.

Screenshots

Version Info 0.5.18 from NuGet.