feat(network): enable ipv6 connection and tunneling (#1114)

Co-authored-by: Quentin McGaw <quentin.mcgaw@gmail.com>

internal/wireguard/rule.go

@@ -6,13 +6,14 @@ import (
 	"github.com/qdm12/gluetun/internal/netlink"
 )
 
-func (w *Wireguard) addRule(rulePriority, firewallMark int) (
+func (w *Wireguard) addRule(rulePriority, firewallMark, family int) (
 	cleanup func() error, err error) {
 	rule := netlink.NewRule()
 	rule.Invert = true
 	rule.Priority = rulePriority
 	rule.Mark = firewallMark
 	rule.Table = firewallMark
+	rule.Family = family
 	if err := w.netlink.RuleAdd(rule); err != nil {
 		return nil, fmt.Errorf("cannot add rule %s: %w", rule, err)
 	}