Fix build with GCC 17

https://bugs.gentoo.org/976979
https://gitlab.com/OpenMW/openmw/-/merge_requests/5346

--- a/apps/wizard/unshield/inisettings.hpp
+++ b/apps/wizard/unshield/inisettings.hpp
@@ -1,6 +1,7 @@
 #ifndef INISETTINGS_HPP
 #define INISETTINGS_HPP
 
+#include <fstream>
 #include <QHash>
 #include <QVariant>