Plugin seems dead, use other sources to check php

I think ultimately a plugin like this is always going to be hard to maintain and make sure that your site is safe. The only real way is to make a 2nd copy of the site and test it thoroughly.

I found detailed info on differences and upgrade procedures listed here https://www.php.net/manual/en/appendices.php

I also keep myself updated on the latest php versions via https://www.updatephp.com