Correct fix for JRuby Zlib error #250

Job	Run time
rubocop	16s
Unit test (ubuntu-20.04, 3)	1m 46s
Unit test (ubuntu-20.04, 3.1)	1m 46s
Unit test (ubuntu-20.04, 3.2)	1m 49s
Unit test (ubuntu-20.04, 3.3)	1m 52s
Unit test (ubuntu-20.04, 3.4)	1m 44s
Unit test (ubuntu-20.04, jruby-9.4)	2m 33s
Unit test (ubuntu-20.04, truffleruby)	3m 52s
Unit test (macos-latest, 3)	1m 34s
Unit test (macos-latest, 3.1)	1m 31s
Unit test (macos-latest, 3.2)	1m 33s
Unit test (macos-latest, 3.3)	1m 34s
Unit test (macos-latest, 3.4)	1m 42s
Unit test (macos-latest, jruby-9.4)	2m 25s
Unit test (macos-latest, truffleruby)	2m 45s
Unit test (windows-latest, 3)	3m 42s
Unit test (windows-latest, 3.1)	3m 32s
Unit test (windows-latest, 3.2)	3m 25s
Unit test (windows-latest, 3.3)	5m 0s
Unit test (windows-latest, 3.4)	4m 21s
finish	3s
	48m 45s

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