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>

plugin/pkg/dnsutil/ttl_test.go

@@ -62,8 +62,7 @@ func BenchmarkMinimalTTL(b *testing.B) {
 	utc := time.Now().UTC()
 	mt, _ := response.Typify(m, utc)
 
-	b.ResetTimer()
-	for range b.N {
+	for b.Loop() {
 		dur := MinimalTTL(m, mt)
 		if dur != 1000*time.Second {
 			b.Fatalf("Wrong MinimalTTL %d, expected %d", dur, 1000*time.Second)