Yes, I used Phaser. Itch.io dashboard allows us to upload html, and it takes javascript. It does not care what else is in there. So you take the phaser.js file and include it in your project if you want to use Phaser. You can include any other web embed - capable projects as well inside "html game". Upload itself is done through the user Dashboard. You "release" the game, then link it to the game jam you are entering.