fix(notification): added event object to test-notification (cross-see…

…d#527)

## Notifiarr test-notification compatibility

Added an `event: "TEST"` in `extra` object to the JSON for
test-notification (`sendTestNotification()`)

It should not affect other apprise integrations.

- [x] test-notification command now works with Notifiarr

src/pushNotifier.ts

@@ -103,6 +103,6 @@ export function initializePushNotifier(): void {
 }
 
 export function sendTestNotification(): void {
-	pushNotifier.notify({ body: "Test" });
+	pushNotifier.notify({ body: "Test", extra: { event: "TEST" } });
 	logger.info("Sent test notification");
 }