Update `str_chilled_p` for Ruby 4.1 #617

Job	Run time
ruby-versions / Generate Ruby versions	3s
windows-latest 3.1	1m 0s
windows-latest 3.4	1m 3s
windows-latest 4.0	58s
windows-latest 2.7	1m 49s
windows-latest mingw	57s
windows-latest 3.3	56s
windows-latest mswin	1m 19s
windows-latest 3.2	1m 9s
windows-latest 3.0	1m 18s
windows-latest jruby-head	1m 40s
	12m 12s

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