Update test_list.cpp
Updating file header to reflect proper attribution
******************************************************************************
Project: OWA EPANET
Version: 2.2
- Module: util/test_list.cpp
- Description: Tests for util/list.c
- Authors: see AUTHORS
+ Module: util/list.h
+ Description: Generic list
+ https://gist.github.com/pseudomuto/6334796#file-sample_app-c
+ Accessed: April 9, 2019
+ Authors: David Muto, Modified by Michael E. Tryby
Copyright: see AUTHORS
License: see LICENSE
Last Updated: 04/09/2019
