DateOnly not supported

The `DateOnly` data type causes a `NotSupportedException` to be thrown when calling `ParseArguments`.

v2.9.1 from Nuget.

```
public class CommandLineOptions
{
[Option('v', "verbose", Required = false, HelpText = "Set output to verbose messages.")]
public bool Verbose { get; set; }

[Option('d', "business-date", Required = true, HelpText = "The date (yyyy-mm-dd) to run the process for.")]
public DateTime Works { get; set; }

[Option('e', "run-date", Required = true, HelpText = "The date (yyyy-mm-dd) to run the process for.")]
public DateOnly Fails { get; set; }
}
```

Workaround: Use `DateTime` instead and do an explicit conversion when property is used `DateOnly.FromDateTime(value);`