Add comprehensive pytest tests and testing infrastructure #5

Job	Run time
Test Environment Validation	6s
Test Python 3.12 on ubuntu-latest	20s
Test Python 3.12 on macos-latest	21s
Test Python 3.12 on windows-latest	34s
Test Install Scripts (ubuntu-latest)	11s
Test Install Scripts (macos-latest)	11s
Test Install Scripts (windows-latest)	22s
Test Summary	0s
	2m 5s

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