Small string fixes for encoding compatibility issues #379

Job	Run time
ruby-versions / Generate Ruby versions	2s
windows-latest 2.7	3m 44s
windows-latest 3.0	2m 22s
windows-latest 3.1	2m 18s
windows-latest 3.2	1m 43s
windows-latest 3.3	1m 43s
windows-latest 3.4	1m 16s
windows-latest jruby-head	1m 26s
windows-latest mingw	2m 9s
windows-latest mswin	1m 10s
	17m 53s

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