Remove deprecated DirectoryOnly file mode in parameter form
DirectoryOnly
is obsolete since Qt 4.5 and is removed in Qt 6: https://doc.qt.io/qt-5/qfiledialog.html#FileMode-enum
DirectoryOnly
is obsolete since Qt 4.5 and is removed in Qt 6: https://doc.qt.io/qt-5/qfiledialog.html#FileMode-enum