String#bytesplice should return self

	In Feature #19314, we concluded that the return value of String#bytesplice
	should be changed from the source string to the receiver, because the source
	string is useless and confusing when extra arguments are added.

	This change should be included in Ruby 3.2.1.
	---
	 string.c                 | 4 ++--
	 test/ruby/test_string.rb | 2 +-
	 2 files changed, 3 insertions(+), 3 deletions(-)