fix: Naming of imports

Author: asafgardin

src/index.ts

@@ -2,6 +2,6 @@ export { AI21 } from './AI21';
 export { VERSION } from './version';
 export * from './types';
 export { AI21Error, MissingAPIKeyError } from './errors';
-export { Stream } from './Streaming';
+export { Stream } from './streaming';
 export { APIResource } from './APIResource';
 export { Chat, Completions } from './resources';

src/resources/chat/completions.ts

@@ -1,6 +1,6 @@
 import * as Models from '../../types';
 import { APIResource } from '../../APIResource';
-import { Stream } from '../../Streaming';
+import { Stream } from '../../streaming';
 
 export class Completions extends APIResource {
   create(