net/dnscache: fix v4addrs to return only v4 addrs

Update the v4addrs function to filter out IPv6 addresses.

Fixes regression from 8725b14056.

Signed-off-by: Kris Brandow <kris.brandow@gmail.com>

net/dnscache/dnscache.go

@@ -614,7 +614,7 @@ func v4addrs(aa []net.IPAddr) (ret []netip.Addr) {
 	for _, a := range aa {
 		ip, ok := netip.AddrFromSlice(a.IP)
 		ip = ip.Unmap()
-		if ok {
+		if ok && ip.Is4() {
 			ret = append(ret, ip)
 		}
 	}