userAgent not set when retrieving sitemap

[nibynool]

Expectation

When using the --sitemap <url> option the defaults.userAgent value from the configuration file will be used. If no default.userAgent is defined then the default as defined at https://github.com/pa11y/pa11y#useragent-string will be used.

Actual

pa11y-ci does not set a useragent when retrieving the sitemap url. Instead it uses the node-fetch default value of node-fetch/1.0 (+https://github.com/bitinn/node-fetch).

Additional info

Version: 2.3.0
Sample config file:

{
  "defaults": {
    "userAgent": "My pa11y-ci test runner"
  }
}