Fix incorrect use of connect/1

Hint from Phoenix 1.4.17, which has a connect/7 shim:

lib/phoenix/socket/transport.ex:

  def connect(endpoint, handler, _transport_name, transport, serializers, params, _pid \\ self()) do
    IO.warn "Phoenix.Socket.Transport.connect/7 is deprecated"

    handler.connect(%{
      endpoint: endpoint,
      transport: transport,
      options: [serializer: serializers],
      params: params
    })
  end

lib/transports.ex

@@ -31,7 +31,7 @@ def init(%Plug.Conn{method: "GET"} = conn, {endpoint, handler, transport}) do
 
     case conn do
       %{halted: false} = conn ->
-        case Transport.connect(%{
+        case handler.connect(%{
                endpoint: endpoint,
                transport: transport,
                options: [serializer: nil],