Add check if interface have ipv6

[ByJacob]

In my case interface docker0 don't have configured ipv6:

"ansible_docker0": {
                "active": false,
                "device": "docker0",
                "id": "8000.0242d12d2f01",
                "interfaces": [],
                "ipv4": {
                    "address": "172.17.0.1",
                    "broadcast": "172.17.255.255",
                    "netmask": "255.255.0.0",
                    "network": "172.17.0.0"
                },
                "macaddress": "02:42:d1:2d:2f:01",
                "mtu": 1500,
                "promisc": false,
                "stp": false,
                "type": "bridge"
            },

And when run role i have error:

fatal: [xxxxxxx]: FAILED! => {"changed": false, "msg": "AnsibleUndefinedVariable: 'list object' has no attribute 'address'"}

I spent some time solving this problem, and it turned out that the code assumes that the interfaces are configured for ipv4 and ipv6

https://github.com/arillso/ansible.hosts/blob/main/templates/etc/hosts.j2#L46-L62

Workaround:

• set hosts_ipv6: false