Only test that sleeps were long enough #30

Job	Run time
RuboCop	33s
specs (ubuntu, 3.0.6)	1m 29s
specs (ubuntu, 3.1.4)	1m 29s
specs (ubuntu, 3.2.2)	1m 25s
specs (ubuntu, 3.3.0)	1m 24s
specs (macos, 3.0.6)	3m 39s
specs (macos, 3.1.4)	4m 6s
specs (macos, 3.2.2)	3m 19s
specs (macos, 3.3.0)	3m 16s
specs (windows, 3.0.6)	4m 7s
specs (windows, 3.1.4)	5m 19s
specs (windows, 3.2.2)	4m 47s
specs (windows, 3.3.0)	4m 50s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 25s
	41m 8s

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