UI: Remove QNetworkReply from window-basic-main.hpp

QNetworkReply was added here in commit
5ba8b09c. Qt5Network was replaced in
commits 13bed1a4 and
39d1cda4, but this one line referring to
QNetworkReply remained. Let's finally remove it.

UI/window-basic-main.hpp

@@ -42,7 +42,6 @@
 class QMessageBox;
 class QListWidgetItem;
 class VolControl;
-class QNetworkReply;
 class OBSBasicStats;
 
 #include "ui_OBSBasic.h"