Provide a development version

Problem/Motivation

There is no development version.

Here's a screenshot of the Flag module

Steps to reproduce

Run composer require drupal/bookmarks:1.x-dev and you will get:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Root composer.json requires drupal/bookmarks 1.x-dev, found drupal/bookmarks[1.0.2] but it does not match the constraint.

Proposed resolution

Maintainer needs to create and push the development branch.