Fix $LOAD_PATH.dup to be Ractor shareable

This fixes an incompatiblity with `did_you_mean`:
https://github.com/ruby/did_you_mean/blob/b5f83b2eeaf6344766174123ccaa7a58ddd579e3/lib/did_you_mean/spell_checkers/require_path_checker.rb#L12

lib/bootsnap/load_path_cache/change_observer.rb

@@ -54,6 +54,18 @@ def uniq!(*args)
             ret
           end
         end
+
+        def dup
+          new_obj = super
+          new_obj.remove_instance_variable(:@lpc_observer)
+          new_obj
+        end
+
+        def clone
+          new_obj = super
+          ChangeObserver.unregister(new_obj)
+          new_obj
+        end
       end
 
       def self.register(arr, observer)