Require Views Bulk Operations in composer.json

It's a soft dependency currently. Project description page should be updated?

I agree. It's a soft dependency currently.

Views Bulk Edit module works just fine without VBO. It can be used with Drupal Core "Node operations bulk form".

Project description page should be updated.

Title of this issue is changed to match the task request.

This tripped me up a bit. The readme has instructions for adding the VBO field.

The project page should clarify that it works for both core and vbo, otherwise the dependencies section makes it look like VBO is required.