If you want to find out which of your composer.json packages have released newer versions, just run composer outdated. You will get a full list with all information, like this below.
1phpdocumentor/type-resolver 0.4.0 0.7.12phpunit/php-code-coverage 6.1.4 7.0.3 Library that provides collection, processing, and rende...3phpunit/phpunit 7.5.9 8.1.3 The PHP Unit Testing framework.4ralouphie/getallheaders 2.0.5 3.0.3 A polyfill for getallheaders.5sebastian/global-state 2.0.0 3.0.0 Snapshotting of global state