[h2c] example should use serve_connection_with_upgrades

Server has to explicitly opt-in to upgrade support.

Author: alexrudy

examples/src/h2c/server.rs

@@ -52,8 +52,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                 let router = h2c.clone();
                 tokio::spawn(async move {
                     let builder = Builder::new(TokioExecutor::new());
-                    let conn = builder
-                        .serve_connection(TokioIo::new(io), TowerToHyperService::new(router));
+                    let conn = builder.serve_connection_with_upgrades(
+                        TokioIo::new(io),
+                        TowerToHyperService::new(router),
+                    );
                     let _ = conn.await;
                 });
             }