Fix/Adopt New DateTime XML Spector Scenario #9991
Description
The new ModelWithDatetime xml scenario is failing since the spector tests expects the rfc3339 property in the request payload to only have 3 digits of precision. For rfc3339, we default to 7 digits.
We should validate what the expected behavior should be for .NET specifically, and/or if the spector test itself needs to be relaxed.