Update hello.ex (#2901)

frameworks/Elixir/cowboy/lib/hello.ex

@@ -7,7 +7,7 @@ defmodule Hello do
     {:ok, _} = :cowboy.start_http(:http,
                                   5000,
                                   [port: 8080],
-                                  [env: [dispatch: dispatch]])
+                                  [env: [dispatch: dispatch], max_keepalive: 5_000_000])
   end
 end