fix: Can't create new users via CLI if username is disabled

[kenjis]

Description
Fixes #1076

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[datamweb]

[CodeIgniter\Database\Exceptions\DataException]

There is no data to insert.

at SYSTEMPATH\BaseModel.php:1703

Backtrace:
  1    SYSTEMPATH\BaseModel.php:1703
       CodeIgniter\Database\Exceptions\DataException::forEmptyDataset('insert')

  2    SYSTEMPATH\BaseModel.php:742
       CodeIgniter\BaseModel()->transformDataToArray([], 'insert')

  3    SYSTEMPATH\Model.php:730
       CodeIgniter\BaseModel()->insert(Object(CodeIgniter\Shield\Entities\User), false)

  4    VENDORPATH\codeigniter4\shield\src\Models\UserModel.php:265
       CodeIgniter\Model()->insert(Object(CodeIgniter\Shield\Entities\User), false)

  5    SYSTEMPATH\BaseModel.php:692
       CodeIgniter\Shield\Models\UserModel()->insert(Object(CodeIgniter\Shield\Entities\User), false)

  6    VENDORPATH\codeigniter4\shield\src\Models\UserModel.php:327
       CodeIgniter\BaseModel()->save(Object(CodeIgniter\Shield\Entities\User))

  7    VENDORPATH\codeigniter4\shield\src\Commands\User.php:304
       CodeIgniter\Shield\Models\UserModel()->save(Object(CodeIgniter\Shield\Entities\User))

  8    VENDORPATH\codeigniter4\shield\src\Commands\User.php:162
       CodeIgniter\Shield\Commands\User()->create(null, 'hghg@fff.it')

  9    SYSTEMPATH\CLI\Commands.php:65
       CodeIgniter\Shield\Commands\User()->run([...])

 10    SYSTEMPATH\CLI\Console.php:37
       CodeIgniter\CLI\Commands()->run('shield:user', [...])

 11    ROOTPATH\spark:97
       CodeIgniter\CLI\Console()->run()