Dependecies prefix coding standard
As described in Let Drupal 8 know about your module with an .info.yml file, the correct format is:


project-name:module-name for third-party modules
drupal:module-name for a core module



  Dependencies should be namespaced in the format: {project}:{module} where {project} is the project name as it appears in the Drupal.org URL (e.g. drupal.org/project/views) and {module} is the module's machine name.


Since the project page for Drupal core is https://www.drupal.org/project/drupal, the case for Drupal core modules is the same as for third-party modules.