Allow drush/drush ^14 for Drupal 12 compatibility

drush 14 (unreleased dev-14.x) drops the consolidation/robo dependency and moves to Symfony-8-ready drupal-code-generator/yaml-cli dev branches -- needed for Drupal 12 core compatibility (Symfony 8). ws_event's drush/drush: ^11 || ^12 || ^13 constraint was the last blocker in the yusaopeny -> y_lb -> ws_event chain preventing drupal/core-recommended:^12@beta from resolving in a D12 upgrade sandbox (ITCR D12 readiness effort).

No code changes needed -- drush 14's public API surface this module touches is unaffected. Constraint widen only.

Will file a tracking issue and link it here once filed.