Plugin not support PHP Code?

Hi,
I’m using this plugin, but I have a problem with PHP Code.

If i write:
<script type="text/javascript" src="<?php bloginfo('template_url'); ?>/wp-content/custom_js/json.debug.js"></script>
I not see the url of my blog, but exactly the code:
<?php bloginfo('template_url'); ?>
why?

Thanks.

https://wordpress.org/plugins/insert-headers-and-footers/