add an unset function for the global provider. fixes #162 #72

Job	Run time
get_version	4s
build-and-run-tests-windows	36m 46s
build-and-run-tests-ubuntu	25m 36s
build-and-run-tests-macos (macos-13)	46m 51s
build-and-run-tests-macos (macos-14)	26m 14s
	2h 15m 31s

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