Small string fixes for encoding compatibility issues #437

Job	Run time
ruby-versions / Generate Ruby versions	2s
ubuntu-24.04 2.7	38s
ubuntu-24.04 3.0	10s
ubuntu-24.04 3.1	12s
ubuntu-24.04 3.2	14s
ubuntu-24.04 3.3	13s
ubuntu-24.04 3.4	11s
ubuntu-24.04 debug	17s
ubuntu-24.04 head	11s
ubuntu-24.04 jruby-head	55s
ubuntu-24.04 truffleruby-head	26s
ubuntu-22.04 2.7	37s
ubuntu-22.04 3.0	10s
ubuntu-22.04 3.1	15s
ubuntu-22.04 3.2	11s
ubuntu-22.04 3.3	15s
ubuntu-22.04 3.4	9s
ubuntu-22.04 debug	31s
ubuntu-22.04 head	11s
ubuntu-22.04 jruby-head	1m 3s
ubuntu-22.04 truffleruby-head	31s
	7m 22s

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