Shrink ruby_bug version guard in anticipation of 3.4.6 release

Fix for this bug was merged into ruby_3_4 in 5a42d26
and should go out in the next 3.4.x release.

Author: XrXr

spec/ruby/language/regexp/character_classes_spec.rb

@@ -562,7 +562,7 @@
     "\u{16EE}".match(/[[:word:]]/).to_a.should == ["\u{16EE}"]
   end
 
-  ruby_bug "#19417", ""..."3.5" do
+  ruby_bug "#19417", ""..."3.4.6" do
     it "matches Unicode join control characters with [[:word:]]" do
       "\u{200C}".match(/[[:word:]]/).to_a.should == ["\u{200C}"]
       "\u{200D}".match(/[[:word:]]/).to_a.should == ["\u{200D}"]