fix: apply suggested change

I like it so I'm keeping it :)

pkg/resolvers/HTTPS.go

@@ -16,7 +16,8 @@ import (
 
 // HTTPSResolver is for DNS-over-HTTPS queries.
 type HTTPSResolver struct {
-	opts util.Options
+	client http.Client
+	opts   util.Options
 }
 
 var _ Resolver = (*HTTPSResolver)(nil)
@@ -25,7 +26,7 @@ var _ Resolver = (*HTTPSResolver)(nil)
 func (resolver *HTTPSResolver) LookUp(msg *dns.Msg) (util.Response, error) {
 	var resp util.Response
 
-	httpR := &http.Client{
+	resolver.client = http.Client{
 		Timeout: resolver.opts.Request.Timeout,
 		Transport: &http.Transport{
 			MaxConnsPerHost:     1,
@@ -56,7 +57,7 @@ func (resolver *HTTPSResolver) LookUp(msg *dns.Msg) (util.Response, error) {
 	req.Header.Set("Accept", "application/dns-message")
 
 	now := time.Now()
-	res, err := httpR.Do(req)
+	res, err := resolver.client.Do(req)
 	resp.RTT = time.Since(now)
 
 	if err != nil {