Fix clippy warning

src/gitlab_webhook.rs

@@ -41,10 +41,7 @@ pub fn build_gitlab_messages(event: &GitlabEvent) -> Vec<String> {
             format!(
                 "\\[{}\\] {}*{}* {}",
                 project.path_with_namespace,
-                refname
+                refname.as_ref().map(|rn| format!("`{}` ", rn)).unwrap_or_default(),
-                    .as_ref()
-                    .map(|rn| format!("`{}` ", rn))
-                    .unwrap_or_else(|| "".to_string()),
                 event.user(),
                 title,
             )