security: fix GPG key listing
    
    Our GPG key list has been subtly broken since bdeb1cc (add opengpgkeys,
    2021-02-15).  The <pre> tag was incomplete and the conditional
    referenced the openpgpkey property as opengpgkey (gpg instead of the
    correct pgp).
    
    Fix both issues so the key listing displays as intended.
    
    Signed-off-by: Todd Zullinger <tmz@pobox.com>