Do not issue warning when calling set_encoding if string is chilled #389

Job	Run time
ruby-versions / Generate Ruby versions	2s
windows-latest 2.7	1m 53s
windows-latest 3.0	2m 17s
windows-latest 3.1	1m 39s
windows-latest 3.2	3m 3s
windows-latest 3.3	3m 11s
windows-latest 3.4	2m 24s
windows-latest jruby-head	3m 25s
windows-latest mingw	1m 3s
windows-latest mswin	1m 54s
	20m 51s

Provide feedback