Remove old checks #2

Job	Run time
ruby-versions / Generate Ruby versions	2s
test (2.5, ubuntu-latest)	30s
test (2.5, macos-latest)	1m 3s
test (2.5, windows-latest)	2m 30s
test (2.6, ubuntu-latest)	41s
test (2.6, macos-latest)	1m 15s
test (2.6, windows-latest)	6m 14s
test (2.7, ubuntu-latest)	45s
test (2.7, macos-latest)	1m 9s
test (2.7, windows-latest)	2m 44s
test (3.0, ubuntu-latest)	20s
test (3.0, macos-latest)	38s
test (3.0, windows-latest)	2m 17s
test (3.1, ubuntu-latest)	32s
test (3.1, macos-latest)	53s
test (3.1, windows-latest)	2m 39s
test (3.2, ubuntu-latest)	25s
test (3.2, macos-latest)	50s
test (3.2, windows-latest)	3m 19s
test (head, ubuntu-latest)	26s
test (head, macos-latest)	45s
test (head, windows-latest)	1m 49s
test (jruby, ubuntu-latest)	6m 46s
test (jruby-head, ubuntu-latest)	5m 21s
test (truffleruby, ubuntu-latest)	2m 49s
test (truffleruby-head, ubuntu-latest)	3m 0s
	49m 42s

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