To install through composer, simply put the following in your composer.json file:

{
    "require": {
        "laravie/webhook": "^2.0",
        "php-http/curl-client": "^2.0"
    }
}

And then run composer install from the terminal.

Above installation can also be simplify by using the following command:

composer require "php-http/curl-client" "laravie/webhook=^2.0"

Instead of utilizing php-http/curl-client you might want to use any other adapter that implements php-http/client-implementation. Check Clients & Adapters for PHP-HTTP.