test(lee): use expect in the emitter test helper

lee/state_machine/src/state/tests/events.rs

@@ -7,7 +7,7 @@ fn program_transaction<T: serde::Serialize>(
 ) -> PublicTransaction {
     let message =
         public_transaction::Message::try_new(program_id, vec![account_id], vec![], instruction)
-            .unwrap();
+            .expect("test instruction must serialize");
     let witness_set = public_transaction::WitnessSet::for_message(&message, &[]);
     PublicTransaction::new(message, witness_set)
 }