Release 4.3.8 (#432)

- Updates payment link request and challenge indicator and exemption. Thank you @Antaris
- Updates card metadata response
- Updates payment response
- Adds Payment context sources
- Adds type property to items in payment context

Author: armando-rodriguez-cko

Directory.Build.props

@@ -1,5 +1,5 @@
 <Project>
     <PropertyGroup>
-        <Version>4.3.7</Version>
+        <Version>4.3.8</Version>
     </PropertyGroup>
 </Project>