fix(template): use the correct function on wry desktop

Use 'main' instead of 'start_app' to start the application.

templates/apps/wry/gen/bin/desktop.rs.hbs

@@ -1,5 +1,5 @@
 
 fn main() {
     #[cfg(not(any(target_os = "android", target_os = "ios")))]
-    {{snake-case app.name}}::start_app().unwrap();
+    {{snake-case app.name}}::main().unwrap();
 }