See possible options here: https://developer.mozilla.org/en-US/docs/Web/API/fetch#options.
RequestInit fields (cache, credentials, mode etc) override the per-call value: they are
process-wide transport policy. Library options (requestTimeout, NUT-19 policy) are defaults a
per-call value overrides. headers merge, per-call wins per key; redirect defaults to error
on requests with a body, and is forced to error on requests carrying auth headers.
An object containing any custom settings that you want to apply to every mint request.