[Bug libstdc++/105375] std::packaged_task has no deduction guide.

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105375

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ah it's noted as a DR at
https://en.cppreference.com/w/cpp/thread/packaged_task#Defect_reports