Solution
Use Composer to manage your project's dependencies and then execute this command to display the packages that have updates available to install:
$ cd your-project/
$ composer outdated
Example
$ composer outdated league/commonmark 0.14.0 0.15.0 Markdown parser for PHP based on the CommonMark spec psr/log 1.0.1 1.0.2 Common interface for logging libraries sensiolabs/security-checker v3.0.2 v4.0.0 A security checker for your composer.lock twig/twig v1.26.0 v1.26.1 The flexible, fast, and secure template language ...