Remove duplicate date_epoch #59

Job	Run time
ruby-versions / Generate Ruby versions	3s
build (3.4, windows-latest)	1m 15s
build (3.4, ubuntu-latest)	24s
build (3.4, macos-latest)	19s
build (head, ubuntu-latest)	16s
build (head, macos-latest)	18s
	2m 35s

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