Added test harness file to .gitignore #872

Job	Run time
Set CI/CD metadata	4s
Commit stage / Check file format	7s
Commit stage / Check Markdown format	9s
Commit stage / Scan secrets	8s
Commit stage / Count lines of code	7s
Commit stage / Scan dependencies	24s
Commit stage / Check English usage	8s
Test stage / Run Util Tests	41s
	1m 48s

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