Change Varbase Workflow module on Drupal core require in composer from ~9.0.0 to ~9.0

Problem/Motivation

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

  Problem 1
    - don't install drupal/varbase_core 9.0.x-dev|install drupal/varbase_core dev-9.0.x
    - vardot/varbase 9.0.x-dev requires drupal/varbase_core 9.0.x-dev -> satisfiable by drupal/varbase_core[9.0.x-dev].
    - vardot/varbase 9.0.x-dev requires drupal/varbase_workflow 2.0.x-dev -> satisfiable by drupal/varbase_workflow[2.0.x-dev].

Proposed resolution

• Change Drupal core require in composer from ~9.0.0 to ~9.0