title: npx sequelize generate:migration --name=[name] keeps failing with Unknown argument: default
body: <p>I'm trying to generate a new migration with Sequelize, but following its help causes an error <code>Unknown argument: default</code>. I installed locally in my project and I am running the commands with <code>npx</code>.</p>
  
  <pre><code>gabriel@gabriel:~/Workspace/authtdd$ npx sequelize migration:generate --name=create_user
  
  Sequelize CLI [Node: 12.4.0, CLI: 5.4.0, ORM: 5.8.7]
  
  Options:
    --help             Show help                                                                                                                                                            [boolean]
    --version          Show version number                                                                                                                                                  [boolean]
    --env              The environment to run the command in                                                                                                        [string] [default: "development"]
    --config           The path to the config file                                                                                                                                           [string]
    --options-path     The path to a JSON file with additional options                                                                                                                       [string]
    --migrations-path  The path to the migrations folder                                                                                                             [string] [default: "migrations"]
    --seeders-path     The path to the seeders folder                                                                                                                   [string] [default: "seeders"]
    --models-path      The path to the models folder                                                                                                                     [string] [default: "models"]
    --url              The database connection string to use. Alternative to using --config files                                                                                            [string]
    --debug            When available show various debug information                                                                                                       [boolean] [default: false]
    --name             Defines the name of the migration                                                                                                                          [string] [required]
    --underscored      Use snake case for the timestamp's attribute names                                                                                                  [boolean] [default: false]
  
  Unknown argument: default
  </code></pre>
  
  <p>But there is the option <code>--name</code> in the help list. Also, I tried a few different approaches: <code>--name:create_user</code>, <code>--name create_user</code>, but they say a "name" required. Same with yarn. Is it a bug?</p>