notifications: make update alerts non-persistent

once acked, they remain acked. no need to keep nagging the user about them.

src/updatechecker.js

@@ -85,7 +85,7 @@ async function checkBoxUpdates(options) {
     const changelog = updateInfo.changelog.map((m) => `* ${m}\n`).join('');
     const message = `Changelog:\n${changelog}\n\nGo to the settings view to update.\n\n`;
 
-    await notifications.alert(notifications.ALERT_BOX_UPDATE, `Cloudron v${updateInfo.version} is available`, message);
+    await notifications.alert(notifications.ALERT_BOX_UPDATE, `Cloudron v${updateInfo.version} is available`, message, { persist: false });
 
     state.box = updateInfo;
     setUpdateInfo(state);