IonTextWriterBuilder write timestamp fails

[jairveder]

When using the IonTextWriterBuilder with IonTextOptions { TimestampAsMillis = false } writing of timestamps result in an System.FormatException.

Example code

{
      using (var tw = new StringWriter())
      using (var writer = IonTextWriterBuilder.Build(tw, new IonTextOptions { TimestampAsMillis = false }))
      {
          writer.Flush();
          writer.StepIn(IonType.Struct);

          writer.SetFieldName("exampleDate");
          writer.WriteTimestamp(new Timestamp(exampleDate));

          writer.StepOut();
          writer.Finish();
      
          command = tw.ToString();
      }
      
      var result = IonLoader.Default.Load(command);
}

Executing this results in the following exception:

Package version: 1.0.1

[simonz-bq]

Moved to amazon-ion/ion-dotnet#132