core: Update required GnuPG version for new archive features

* src/engine-gpg.c (gpg_decrypt, gpg_encrypt, gpg_encrypt_sign,
gpg_sign, gpg_verify): Require gpg 2.4.1.

To work properly the archive feature needs a fix added in GnuPG 2.4.1.

• GnuPG-bug-id: T6342