use fetch() instead of axios()

[bordalix]

Why we need to stop using axios and start using fetch:

• Google is enforcing Chrome extensions to adopt Manifest v3.
• With Manifest v3 it is mandatory to use service workers instead of the background script.
• Workers no longer provide XMLHttpRequest, but instead support the more modern fetch().
• Since axios uses XMLHttpRequest, it will not work under a service worker.
• So this module it will not work if included in a new Chrome extension.

@tiero please review

[tiero]

Looks good to me, although I would wait to merge for this change until we understand how we can move to manifest v3 safely (wasm support missing)