fix comment

Author: greg-rychlewski

lib/ecto/adapters/myxql.ex

@@ -539,10 +539,10 @@ defmodule Ecto.Adapters.MyXQL do
     {args, cmd_opts}
   end
 
-  // Largely ported from Elixir System.cmd implementation
-  // with the intent of using file redirection for passing
-  // dump files into the mysql client so that users don't
-  // run into shell limits when dump files are large
+  # Largely ported from Elixir System.cmd implementation
+  # with the intent of using file redirection for passing
+  # dump files into the mysql client so that users don't
+  # run into shell limits when dump files are large
   defp run_with_port(cmd, opts, opt_args, contents, cmd_opts \\ []) do
     unless System.find_executable(cmd) do
       raise "could not find executable `#{cmd}` in path, " <>