message: Set ip_strategy by ipv6_first while reading from system config
  ref
diff: @@ -46,7 +46,7 @@ pub async fn create_resolver(
  } else {
  use trust_dns_resolver::system_conf::read_system_conf;
  // use the system resolver configuration
  - let (config, opts) = match read_system_conf() {
  + let (config, mut opts) = match read_system_conf() {
  Ok(o) => o,
  Err(err) => {
  error!("failed to initialize DNS resolver with system-config, error: {}", err);
  @@ -58,6 +58,11 @@ pub async fn create_resolver(
  };
  // NOTE: timeout will be set by config (for example, /etc/resolv.conf on UNIX-like system)
  + //
  + // Only ip_strategy should be changed
  + if ipv6_first {
  + opts.ip_strategy = LookupIpStrategy::Ipv6thenIpv4;
  + }
  trace!(
  "initializing DNS resolver with system-config {:?} opts {:?}",
  