Specify type of uint variable xmin explicitely

Author: simon-wacker

backend/src/GraphQl/Entities/EntityType.cs

@@ -31,6 +31,7 @@ IObjectTypeDescriptor<TEntity> descriptor
             // TODO Do we want to expose this, require it as input, and use it to discover concurrent writes?
             descriptor
               .Field(t => t.xmin)
+              .Type<NonNullType<NonNegativeIntType>>()
               .Name("version")
               .Ignore();
         }