Fix warning on SQL Browser startup

Browser::addConnection is not a slot/invokable, and requires arguments.

What was probably meant to happen is that the connection dialog
opens.

Pick-to: 6.5 6.6 6.7
Change-Id: I4e6bffb3e0277ca3deb7111cf4bb47ff188f6f16
Reviewed-by: Christian Ehrlicher <ch.ehrlicher@gmx.de>

examples/sql/sqlbrowser/main.cpp

@@ -48,7 +48,8 @@ int main(int argc, char *argv[])
     addConnectionsFromCommandline(app.arguments(), &browser);
     mainWin.show();
     if (QSqlDatabase::connectionNames().isEmpty())
-        QMetaObject::invokeMethod(&browser, "addConnection", Qt::QueuedConnection);
+        QMetaObject::invokeMethod(&browser, &Browser::openNewConnectionDialog,
+                                  Qt::QueuedConnection);
 
     return app.exec();
 }