traprain: Fix sequoia-gpgv conflict

traprain test needs to install devscripts which depends on gnupg2 packages,
and ultimately on gpgv package. When running on target board which embed
the sequoia-gpgv replacement, the installation procedure fails due to the
conflict between sequoia-gpgv and gpgv.
gpgv package should be explicitly installed to replace sequoia-gpgv.

frome and rhosydd have the same dependency problem.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>