Removed singleton dependency #149

Job	Run time
ruby-versions / Generate Ruby versions	3s
build (2.4 / ubuntu-latest)	23s
build (2.4 / macos-latest)	1m 15s
build (2.5 / ubuntu-latest)	23s
build (2.5 / macos-latest)	48s
build (2.6 / ubuntu-latest)	24s
build (2.6 / macos-latest)	1m 7s
build (2.7 / ubuntu-latest)	23s
build (2.7 / macos-latest)	52s
build (3.0 / ubuntu-latest)	12s
build (3.0 / macos-latest)	24s
build (3.1 / ubuntu-latest)	14s
build (3.1 / macos-latest)	26s
build (3.2 / ubuntu-latest)	12s
build (3.2 / macos-latest)	30s
build (3.3 / ubuntu-latest)	14s
build (3.3 / macos-latest)	31s
build (head / ubuntu-latest)	18s
build (head / macos-latest)	18s
	8m 57s

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