Mercurial: Convert to Tr::tr

Change-Id: I2a6ecd17091ffa0100f982848afbf941c6997db7
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/mercurial/authenticationdialog.h

@@ -13,8 +13,6 @@ namespace Mercurial::Internal {
 
 class AuthenticationDialog : public QDialog
 {
-    Q_OBJECT
-
 public:
     explicit AuthenticationDialog(const QString &username, const QString &password,
                                   QWidget *parent = nullptr);