fix: request body type

[achingbrain]

Fixes two problems:

1. The import for NodeReadableStream was missing
2. We can't use NodeReadableStream as the type for body because it it not assignable to any type that makes up BodyInit so instead modify the RequestInit type to omit the original body type and include the new one.

Fixes this error:

node_modules/ipfs-utils/dist/src/types.d.ts:11:18 - error TS2430: Interface 'FetchOptions' incorrectly extends interface 'RequestInit'.
  Types of property 'body' are incompatible.
    Type 'Readable | BodyInit | null | undefined' is not assignable to type 'BodyInit | null | undefined'.
      Type 'Readable' is not assignable to type 'BodyInit | null | undefined'.
        Type 'Readable' is missing the following properties from type 'ReadableStream<Uint8Array>': locked, cancel, getReader, pipeThrough, and 2 more.

11 export interface FetchOptions extends RequestInit {
                    ~~~~~~~~~~~~


Found 1 error.

[achingbrain]

Refs: textileio/js-powergate-client#430

[Gozala]

Mode some suggestions, but works as is too

[Gozala]

I think following would be more obvious.

export type FetchOptions = Override<RequestInit, { body?: ... }> & {
   ...
}