Bump actions/checkout from 4 to 5 (#140) #423

Job	Run time
ruby-versions / Generate Ruby versions	4s
windows-latest 2.7	1m 21s
windows-latest mingw	1m 13s
windows-latest 3.4	54s
windows-latest 3.1	45s
windows-latest 3.2	1m 12s
windows-latest 3.3	51s
windows-latest jruby-head	2m 28s
windows-latest 3.0	45s
windows-latest mswin	1m 9s
	10m 42s

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