Fix build with GCC 14
Removed non-compiling assignment operator. Fixed #718
Downstream report: https://bugs.gentoo.org/914581
See also: https://github.com/Tencent/rapidjson/issues/718
Signed-off-by: Andreas Sturmlechner asturm@gentoo.org (cherry-picked from rapidjson upstream commit 3b2441b87f99ab65f37b141a7b548ebadb607b96)
It seems to be impossible to get things upstreamed (see for example https://codereview.qt-project.org/c/qt/qtlocation/+/454093) which is why this is here instead.