use a more modern writing style to simplify code (#7182)

Signed-off-by: joemicky <joemickychang@outlook.com>
Co-authored-by: Matt Holt <mholt@users.noreply.github.com>

modules/caddyhttp/encode/encode_test.go

@@ -9,7 +9,7 @@ import (
 
 func BenchmarkOpenResponseWriter(b *testing.B) {
 	enc := new(Encode)
-	for n := 0; n < b.N; n++ {
+	for b.Loop() {
 		enc.openResponseWriter("test", nil, false)
 	}
 }