gnupg2: updated to 2.2.4

Noteworthy changes in version 2.2.4:
  * gpg: Change default preferences to prefer SHA512.
  * gpg: Print a warning when more than 150 MiB are encrypted using a
    cipher with 64 bit block size.
  * gpg: Print a warning if the MDC feature has not been used for a
    message.
  * gpg: Fix regular expression of domain addresses in trust
    signatures.
  * agent: New option --auto-expand-secmem to help with high numbers
    of concurrent connections.  Requires libgcrypt 1.8.2 for having
    an effect.
  * dirmngr: Cache responses of WKD queries.
  * gpgconf: Add option --status-fd.
  * wks: Add commands --check and --remove-key to gpg-wks-server.
  * Increase the backlog parameter of the daemons to 64 and add
    option --listen-backlog.
  * New configure option --enable-run-gnupg-user-socket to first try a
    socket directory which is not removed by systemd at session end.

(adam)