fix(tests): backport updater test fix from tauri (#404)

plugins/updater/tests/app-updater/src/main.rs

@@ -34,9 +34,11 @@ fn main() {
             tauri::async_runtime::spawn(async move {
                 match handle.updater().check().await {
                     Ok(update) => {
-                        if let Err(e) = update.download_and_install(|_event| {}).await {
+                        if update.is_update_available() {
-                            println!("{e}");
+                            if let Err(e) = update.download_and_install(|_event| {}).await {
-                            std::process::exit(1);
+                                println!("{e}");
+                                std::process::exit(1);
+                            }
                         }
                         std::process::exit(0);
                     }