Format nullary protocols better in the error msg

Author: ngernest

protocols/src/diagnostic.rs

@@ -488,7 +488,7 @@ impl DiagnosticHandler {
                 "Expressions must be in the same file for assertion error"
             );
             let transaction_call = if todo_args.is_empty() {
-                tr.name.clone()
+                format!("{}()", tr.name)
             } else {
                 let args_str = todo_args
                     .iter()

protocols/tests/brave_new_world/failure_to_update/ftu_sha_bug.out

@@ -1,4 +1,4 @@
-error: The two expressions did not evaluate to the same value (in transaction `failure_to_update_sha`)
+error: The two expressions did not evaluate to the same value (in transaction `failure_to_update_sha()`)
    ┌─ brave_new_world/failure_to_update/ftu_sha.prot:29:15
    │
 29 │     assert_eq(dut.valid, 1'b0);