Update lib/rexml/parsers/baseparser.rb

Co-authored-by: Sutou Kouhei <[email protected]>

lib/rexml/parsers/baseparser.rb

@@ -232,7 +232,7 @@ def pull_event
               if md.nil?
                 raise REXML::ParseException.new("Unclosed comment", @source)
               end
-              if md[1] =~ /--|-\z/
+              if /--|-\z/.match?(md[1])
                 raise REXML::ParseException.new("Malformed comment", @source)
               end
               return [ :comment, md[1] ]