Gc\Core\Updater\Adapter\Git::upgrade PHP Method

    public function upgrade()
    {
        putenv('PATH=' . getenv('PATH') . ':' . GC_APPLICATION_PATH);
        exec('git checkout ' . $this->getLatestVersion() . ' 2>&1', $output);
        $this->addMessage(implode(PHP_EOL, $output));
        return true;
    }