Remove duplicate unused QVariantMap attr in isWinnable

src/gamestate.cpp

@@ -899,7 +899,6 @@ QVariant GameState::isWinnable() const {
         // there doesn't seem to be an easy way to specify that this is null from C++
         map["winnable"] = QVariant();
     }
-    map["optionalBool"] = m_isWinnable.first.has_value() ? QVariant(m_isWinnable.first.value()) : QVariant::fromValue(QVariant());
     map["depth"] = m_isWinnable.second;
     return map;
 }