Fix URL ip_last_octet regex (#145)

* Fix URL ip_last_octet regex

Allow URLs using IPs ending with 0 and 255, depending on the cidr they can be used.

Exemple:
- Network: 172.16.0.0/16
- Usable IP addresses: 172.16.0.1 -> 172.16.255.254

* Change IPv4 test cases

Allow URLs using IPs ending with 0 and 255, depending on the cidr they can be used.

Example:

    Network: 172.16.0.0/16
    Usable IP addresses: 172.16.0.1 -> 172.16.255.254

Co-authored-by: DrStacheWH <drstache.wh@gmail.com>

Author: kvesteri