Update src/engine.ml

Co-authored-by: Reynir Björnsson <[email protected]>

src/engine.ml

@@ -572,7 +572,7 @@ let push_request tls =
     (Tls.Engine.send_application_data tls [ Packet.push_request ])
 
 let push_reply tls data =
-  (* a trailing 0 byte.. (String.make 1 '\000') *)
+  (* a trailing 0 byte.. ("\000") *)
   let repl =
     String.concat "" [ Packet.push_reply; data; "\000" ]
   in