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