Missing project dependencies

[ghost]

Hi,
after composer update I'm getting following error:

~/app$ vendor/bin/dep
You need to set up the project dependencies using the following commands:
wget http://getcomposer.org/composer.phar
php composer.phar install

composer.json file is in ~/app directory. There wasn't any problems before update. It's a Laravel app, I want to update to version 9 of this framework. Any ideas how to fix it?