security/vuxml: Mark zeek < 4.0.6 as vulnerable as per:

    https://github.com/zeek/zeek/releases/tag/v4.0.6

 - Fix potential unbounded state growth in the FTP analyzer when
   receiving a specially-crafted stream of commands. This may lead
   to a buffer overflow and cause Zeek to crash. Due to the possibility
   of this happening with packets received from the network, this
   is a potential DoS vulnerabilty.

Reported by:    Tim Wojtulewicz