Remove extra trailing comma that causes an error when updating via composer

Here's the error message and composer update is ran:
>Loading composer repositories with package information
>Reading composer.json of https://github.com/ZF-Commons/ZfcUser (master)  
>Skipped branch master, "https://api.github.com/repos/ZF-Commons/ZfcUser/contents/composer.json?ref=8835f64cf469c1fb8e5ff887f530028ca48a6c48" does not contain valid JSON
>Parse error on line 20:
>...       }    ],    {    "extra": {   
>---------------------^
>Expected: 'STRING' - It appears you have an extra trailing comma