urlBase and siteId is required even when disabled is true

[gky360]

Describe the bug

When creating a MatomoTracker, it raises an error if urlBase or siteId is empty value even when disabled is true.

To Reproduce

Run the following code.

import MatomoTracker from '@datapunt/matomo-tracker-js'

const tracker = new MatomoTracker({
  urlBase: '',
  siteId: 1,
  disabled: true,
})

Expected behavior

We can create MatomoTracker without an error with empty urlBase or siteId when disabled is true.