Do not play notification sounds on Oreo or later

On devices with Android 8.0 (Oreo) or later, notification sound will be handled by the system, if notifications have not been disabled by the user.

Signed-off-by: Dariusz Olszewski <starypatyk@users.noreply.github.com>

app/src/main/java/com/nextcloud/talk/jobs/NotificationWorker.java

@@ -491,6 +491,11 @@ public class NotificationWorker extends Worker {
         NotificationManagerCompat notificationManager = NotificationManagerCompat.from(context);
         notificationManager.notify(notificationId, notification);
 
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            // On devices with Android 8.0 (Oreo) or later, notification sound will be handled by the system
+            // if notifications have not been disabled by the user.
+            return;
+        }
 
         if (!notification.category.equals(Notification.CATEGORY_CALL) || !muteCall) {
             String ringtonePreferencesString;