Restore assembly attribute token for portable testing

Author: StephenMolloy

src/libraries/Microsoft.XmlSerializer.Generator/tests/Expected.SerializableAssembly.XmlSerializers.cs

@@ -1,7 +1,7 @@
 [assembly:System.Security.AllowPartiallyTrustedCallers()]
 [assembly:System.Security.SecurityTransparent()]
 [assembly:System.Security.SecurityRules(System.Security.SecurityRuleSet.Level1)]
-[assembly:System.Xml.Serialization.XmlSerializerVersionAttribute(ParentAssemblyId=@"47db0224-c12e-4fcb-a7a7-501bba3513a0,", Version=@"1.0.0.0")]
+[assembly:System.Xml.Serialization.XmlSerializerVersionAttribute(ParentAssemblyId=@"%%ParentAssemblyId%%", Version=@"1.0.0.0")]
 namespace Microsoft.Xml.Serialization.GeneratedAssembly {
 
     public class XmlSerializationWriter1 : System.Xml.Serialization.XmlSerializationWriter {