Composer install 报错：laravel/horizon v1.4.3 requires ext-pcntl * -> the requested PHP extension pcntl

错误提示：

laravel/horizon v1.4.3 requires ext-pcntl * -> the requested PHP extension pcntl is missing from your system

解决办法：

在 composer.json 中增加

    "config": {
        "preferred-install": "dist",
        "sort-packages": true,
        "optimize-autoloader": true,
        "platform": {
            "ext-pcntl": "7.2",
            "ext-posix": "7.2"
        }
    }