SvgHandler might access out of bound

The following code does not check the length of family before accessing the first character:

https://codebrowser.dev/qt5/qtsvg/src/svg/qsvghandler.cpp.html#1382

if (!attributes.fontFamily.isEmpty() && attributes.fontFamily != QT_INHERIT) {
        QString family = attributes.fontFamily.toString().trimmed();
        if (family.at(0) == QLatin1Char('\'') || family.at(0) == QLatin1Char('\"'))
            family = family.mid(1, family.size() - 2);
        fontStyle->setFamily(family);