Action Text ReDoS (Ruby 3.1 or lower)

I have found ReDoS in Action Text. However, it does not occur with Ruby 3.2 or later.

https://github.com/rails/rails/blob/v7.1.3.2/actiontext/lib/action_text/plain_text_conversion.rb#L64

      def plain_text_for_blockquote_node(node, index)
        text = plain_text_for_block(node)
        text.sub(/\A(\s*)(.+?)(\s*)\Z/m, '\1“\2”\3')
      end