Bump GraphQL to 8.0.0 (#70)

Author: Shane32

Directory.Build.props

@@ -20,8 +20,7 @@
     <ImplicitUsings>true</ImplicitUsings>
     <Nullable>enable</Nullable>
     <IsPackable>false</IsPackable>
-    <!--<GraphQLVersion>[8.0.0,9.0.0)</GraphQLVersion>-->
-    <GraphQLVersion>8.0.0-preview-1068</GraphQLVersion>
+    <GraphQLVersion>8.0.0</GraphQLVersion>
     <NoWarn>$(NoWarn);IDE0056;IDE0057;NU1902;NU1903</NoWarn>
   </PropertyGroup>