chore(internal): remove unused streaming implementation (#150)

src/core.ts

@@ -1,6 +1,5 @@
 import * as qs from 'qs';
 import { VERSION } from './version';
-import { Stream } from './streaming';
 import { APIError, APIConnectionError, APIConnectionTimeoutError, APIUserAbortError } from './error';
 import type { Readable } from 'modern-treasury/_shims/node-readable';
 import { getDefaultAgent, type Agent } from 'modern-treasury/_shims/agent';
@@ -252,12 +251,6 @@ export abstract class APIClient {
       throw err;
     }
 
-    if (options.stream) {
-      // Note: there is an invariant here that isn't represented in the type system
-      // that if you set `stream: true` the response type must also be `Stream<T>`
-      return new Stream<Rsp>(response, controller) as any;
-    }
-
     const contentType = response.headers.get('content-type');
     if (contentType?.includes('application/json')) {
       const json = await response.json();