message: fix expected error type
diff: @@ -47,7 +47,7 @@ async def test_pack_message_invalid_receiver_verkey(wallet_handle, verkey_my2, i
  receiver_verkeys = verkey_my2
  with pytest.raises(IndyError) as e:
  await crypto.pack_message(wallet_handle, pack_message, receiver_verkeys, sender_verkey)
  - assert ErrorCode.CommonInvalidStructure == e.value.error_code
  + assert ErrorCode.CommonInvalidParam4 == e.value.error_code
  @pytest.mark.asyncio
  