remove axios dependency

[mlavina]

I wanted to use this library in a Deno project and one of the only things stopping me is the dependency on axios which seemed unnecessary so I replaced it with Fetch. So now it's all native libraries, literally 0 dependencies.

[ChiriVulpes]

I didn't know node 18 came with fetch, that's awesome. Since this will require a higher node version we'll bump the scryfall-sdk's major version for this. Thanks!