fixup! Add example implementation using async source

Author: matthiasbeyer

examples/async_source/main.rs

@@ -31,7 +31,7 @@ async fn run_server() -> Result<(), Box<dyn Error>> {
 
 async fn run_client() -> Result<(), Box<dyn Error>> {
     // Good enough for an example to allow server to start
-    tokio::time::delay_for(tokio::time::Duration::from_secs(3)).await;
+    tokio::time::sleep(tokio::time::Duration::from_secs(3)).await;
 
     let config = ConfigBuilder::<AsyncState>::default()
         .add_async_source(HttpSource {