✨ Mark async main function with #[pagetop::main]

Also, use #[pagetop::test] for test functions. Add actix-web to
Cargo.toml only when using Actix Web macros for service configuration.

examples/basics/hello-name/src/main.rs

@@ -25,7 +25,7 @@ async fn hello_name(
         .render()
 }
 
-#[actix_web::main]
+#[pagetop::main]
 async fn main() -> std::io::Result<()> {
     Application::prepare(&HelloName).unwrap().run()?.await
 }