Exigir la versión de Forked en Composer

He leído esto en muchos otros lugares, pero por alguna razón, esto no parece funcionar para mí. Nunca saca la versión del repository bifurcado? Esto es lo que trato de hacer: https://github.com/Jafo232/laravel-medialibrary/tree/v3

Aquí está mi file de compositor:

{ "name": "laravel/laravel", "description": "The Laravel Framework.", "keywords": ["framework", "laravel"], "license": "MIT", "type": "project", "repositories": [ { "type": "vcs", "url": "https://github.com/Jafo232/laravel-medialibrary" } ], "require": { "php": ">=5.6.4", "barryvdh/laravel-debugbar": "^2.2", "ixudra/curl": "^6.10", "jenssegers/model": "^1.1", "laracasts/flash": "^2.0", "laravel/framework": "5.4.*", "laravel/tinker": "~1.0", "spatie/laravel-medialibrary": "v3" }, "require-dev": { "fzaninotto/faker": "~1.4", "mockery/mockery": "0.9.*", "laravelcollective/html": "~5.0", "phpunit/phpunit": "~5.7" }, "autoload": { "classmap": [ "database" ], "psr-4": { "App\\": "app/" } }, "autoload-dev": { "psr-4": { "Tests\\": "tests/" } }, "scripts": { "post-root-package-install": [ "php -r \"file_exists('.env') || copy('.env.example', '.env');\"" ], "post-create-project-cmd": [ "php artisan key:generate" ], "post-install-cmd": [ "Illuminate\\Foundation\\ComposerScripts::postInstall", "php artisan optimize" ], "post-update-cmd": [ "Illuminate\\Foundation\\ComposerScripts::postUpdate", "php artisan optimize" ] }, "config": { "sort-packages": true } }