freebsd-update: rsautl is deprecated, use pkeyutl

The command openssl-rsautl(1) has been deprecated in OpenSSL 3.0. The
openssl-pkeyutl(1) command should be used instead.

Signed-off-by: Jose Luis Duran <jlduran@gmail.com>
Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1309