removed useless Arc clone and spawn when not serialising

src/main.rs

@@ -139,7 +139,12 @@ async fn normal(cfg: config::Config) -> eyre::Result<()>
 	cfg_if!{
 	    if #[cfg(feature="inspect")] {
 		let graph = Arc::new(graph);
-		(Arc::clone(&graph), OptionFuture::from(Some(tokio::spawn(write_graph(graph)))))
+		let (g, w) = if cfg.serialise_output.is_some() {
+		    (Arc::clone(&graph), Some(tokio::spawn(write_graph(graph))))
+		} else {
+		    (graph, None)
+		};
+		(g, OptionFuture::from(w))
 	    } else {
 		(graph, OptionFuture::from(Option::<futures::future::BoxFuture<'static, ()>>::None))
 	    }