update protobuf example

basics/hello-world/src/main.rs

@@ -17,7 +17,7 @@ async fn main() -> std::io::Result<()> {
             .service(web::resource("/index.html").to(|| async { "Hello world!" }))
             .service(web::resource("/").to(index))
     })
-    .bind("127.0.0.1:8080")?
+    .bind(("127.0.0.1", 8080))?
     .run()
     .await
 }