ports/67069: Update port: net/bnbt - security update (DoS vulnerability found)

[Oliver Eikemeier]

Since this addressed a security vulnerability, you might
want to check if there is already an entry in

   ports/security/vuxml/vuln.xml
or
   ports/security/portaudit-db/database/portaudit.txt

next time (Not both, the first is preferred).

This one has already been added, but of course we depend
on your cooperation to keep the database up to date.

Thanks
-Oliver