Clippy fix

src/test_utils.rs

@@ -530,10 +530,7 @@ impl TestContext {
             Contact::add_or_lookup(self, &name, &addr, Origin::MailinglistAddress)
                 .await
                 .expect("add_or_lookup")
-                .expect(&format!(
-                    "contact with address {:?} cannot be created",
-                    &addr
-                ));
+                .unwrap_or_else(|| panic!("contact with address {:?} cannot be created", &addr));
         match modified {
             Modifier::None => (),
             Modifier::Modified => warn!(&self.ctx, "Contact {} modified by TestContext", &addr),