fix(rpc-plugin): failed to execute 'fetch' on browser

[homaily]

Hi @kerimovok,

This PR fixes default fetch missing its correct context when the client used on browser.

currently using the client on browser will throw an error Failed to execute 'fetch' on 'Window': Illegal invocation.

It could be fixed on client initialization by passing a wrapper function (example below) but that's not ideal

new ApiClient('http://localhost:3000', {
  fetchFn: (...args) => fetch(...args),
})

[kerimovok]

Thanks for the PR, @homaily!