Magestead\Installers\Magento2Project::setComposerBinDir PHP Method

    protected function setComposerBinDir($projectPath)
    {
        $file = "{$projectPath}/public/composer.json";
        $composer = json_decode(file_get_contents($file), true);
        $composer['config']['bin-dir'] = 'bin';
        file_put_contents($file, json_encode($composer));
    }