community/megasdk: glibcxx assertions trip on tests

disabled in 1728d84a

[----------] 2 tests from User
[ RUN      ] User.serialize_unserialize
/usr/include/c++/13.1.1/bits/shared_ptr_base.h:1349: std::__shared_ptr_access<_Tp, _Lp, <anonymous>, <anonymous> >::element_type& std::__shared_ptr_access<_Tp, _Lp, <anonymous>, <anonymous> >::operator*() const [with _Tp = mega::Waiter; __gnu_cxx::_Lock_policy _Lp = __gnu_cxx::_S_atomic; bool <anonymous> = false; bool <anonymous> = false; element_type = mega::Waiter]: Assertion '_M_get() != nullptr' failed.
Aborted

actual bug, should be fixed