chore(lint): modernize Go (#7536)

Use modern Go constructs through the modernize analyzer from the
golang.org/x/tools package.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

core/dnsserver/server.go

@@ -4,6 +4,7 @@ package dnsserver
 import (
 	"context"
 	"fmt"
+	"maps"
 	"net"
 	"runtime"
 	"runtime/debug"
@@ -99,9 +100,7 @@ func NewServer(addr string, group []*Config) (*Server, error) {
 		}
 
 		// copy tsig secrets
-		for key, secret := range site.TsigSecret {
-			s.tsigSecret[key] = secret
-		}
+		maps.Copy(s.tsigSecret, site.TsigSecret)
 
 		// compile custom plugin for everything
 		var stack plugin.Handler

core/dnsserver/server_grpc.go

@@ -62,7 +62,7 @@ func (s *ServergRPC) Serve(l net.Listener) error {
 	s.m.Unlock()
 
 	if s.Tracer() != nil {
-		onlyIfParent := func(parentSpanCtx opentracing.SpanContext, method string, req, resp interface{}) bool {
+		onlyIfParent := func(parentSpanCtx opentracing.SpanContext, method string, req, resp any) bool {
 			return parentSpanCtx != nil
 		}
 		intercept := otgrpc.OpenTracingServerInterceptor(s.Tracer(), otgrpc.IncludingSpans(onlyIfParent))

core/dnsserver/server_test.go

@@ -115,8 +115,8 @@ func BenchmarkCoreServeDNS(b *testing.B) {
 	m.SetQuestion("aaa.example.com.", dns.TypeTXT)
 
 	b.ReportAllocs()
-	b.ResetTimer()
-	for range b.N {
+
+	for b.Loop() {
 		s.ServeDNS(ctx, w, m)
 	}
 }