bug: task help generation via option() doesn't work

Repro

const { task, logger, option, argv } = require('just-task');

option('name', {describe: 'user name or something'});

task('blimey', 'An exclamation of surprise.', function() {
  logger.info(`blimey! ${argv().name}`);
});

Actual behaviour

Basically --help output always invokes yargs default help command.

just --help

just blimey --help

Expected behaviour

just blimey --help

Options:
  --name    user name or something                                                 [string]
  --help     Show help                                                 [boolean]
  --version  Show version number                                       [boolean]

Start by running the reported just blimey --help reproduction and tracing how option() registrations reach help generation. The fix is done when task-specific options such as --name, along with help and version entries, appear instead of only the default help output.