Add jruby-head to macos CI builds #425

Job	Run time
ruby-versions / Generate Ruby versions	4s
windows-latest jruby-head	1m 23s
windows-latest 3.4	59s
windows-latest 3.2	50s
windows-latest 3.1	1m 1s
windows-latest mingw	51s
windows-latest 3.3	1m 32s
windows-latest mswin	1m 17s
windows-latest 2.7	1m 15s
windows-latest 3.0	46s
	9m 58s

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