1.0.2: Updated for case sensitivity (OSK-5) (#6)

Motivation
----
Current package fails to find property names if they aren't matching case. This should be based on the JsonSerializationOptions rather than asusmed

Modifications
----
* Updated package for Utf8JsonReaderExtensions which includes new overload for case sensitivity
* Updated PolymorphismJsonConverter to use new extension
* Added UnitTest to validate failing use case is passing

Result
----
Case sensitivity on deserialization is respected based on JsonSerializationOptions settings