Make benchmarks JRuby compatible #795

Job	Run time
Ruby memcheck	54s
ruby-versions / Generate Ruby versions	2s
ubuntu-latest 2.7	1m 2s
ubuntu-latest 3.0	40s
ubuntu-latest 3.1	42s
ubuntu-latest 3.2	41s
ubuntu-latest 3.3	38s
ubuntu-latest 3.4	39s
ubuntu-latest head	1m 35s
ubuntu-latest jruby	1m 5s
ubuntu-latest jruby-head	1m 10s
macos-14 2.7	48s
macos-14 3.0	23s
macos-14 3.1	45s
macos-14 3.2	18s
macos-14 3.3	20s
macos-14 3.4	27s
macos-14 head	19s
macos-14 jruby	38s
macos-14 jruby-head	47s
windows-latest 2.7	4m 9s
windows-latest 3.0	2m 22s
windows-latest 3.1	2m 49s
windows-latest 3.2	2m 21s
windows-latest 3.3	3m 14s
windows-latest 3.4	3m 52s
windows-latest head	1m 29s
ubuntu-24.04-arm 3.4	44s
macos-13 3.4	39s
windows-latest mswin	1m 15s
ubuntu-latest jruby-9.4	1m 5s
macos-latest truffleruby-head	47s
ubuntu-latest truffleruby-head	2m 12s
	40m 51s

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