[ruby/prism] Turn off unescape tests for Ruby >= 3.4.0

ruby/prism@f982769314

Author: kddnewton

test/prism/unescape_test.rb

@@ -2,7 +2,9 @@
 
 require_relative "test_helper"
 
-return if RUBY_VERSION < "3.1.0" || Prism::BACKEND == :FFI
+return if Prism::BACKEND == :FFI
+return if RUBY_VERSION < "3.1.0"
+return if RUBY_VERSION >= "3.4.0"
 
 module Prism
   class UnescapeTest < TestCase