Upgrading bootstrap and php version

As a web developer, I have been tasked with upgrading Bootstrap and PHP versions on a current website. The current versions that are being used are Bootstrap 3 and PHP 5. The main reason for the upgrade is to ensure security and performance updates are implemented. In addition to the upgrades, I will also be adding a list of additional features and functionalities. It is important to make sure the new versions of Bootstrap and PHP are fully compatible with the latest web technologies. I want to make sure the website is properly updated and secure while delivering a great user experience.