fix file upload example

examples/file_upload.rs

@@ -3,7 +3,7 @@ use dioxus::prelude::*;
 use tokio::time::sleep;
 
 fn main() {
-    dioxus_desktop::launch(app);
+    dioxus_desktop::launch(App);
 }
 
 fn App(cx: Scope) -> Element {