composer require 'drupal/varnish_purge' does not install dependencies

Problem/Motivation

When installing Varnish purger throughcomposer require 'drupal/varnish_purge' the required purge modules are not installed.

Steps to reproduce

Run composer require 'drupal/varnish_purge'

Proposed resolution

Add a composer.json file that lists the project dependencies.

Remaining tasks

1. Write a merge request
2. Review
3. Commit

User interface changes

None

API changes

None

Data model changes

None