qt: Port to new setExpire()
* lang/qt/src/qgpgmechangeexpiryjob.cpp (change_expiry): Use new setExpire() instead of edit() with GpgSetExpiryTimeEditInteractor
Using the new setExpire() (which uses --quick-set-expire) is a lot less
complex than using gpg's edit interface. It also feels faster. Next,
I'll add support for changing the expiration time of subkeys.
- GnuPG-bug-id: T5003