exported required scopes file in index.js of slack packages

packages/slack/src/index.ts

@@ -29,3 +29,4 @@ export * from './utils/post-ephemeral-errors';
 export * from './utils/reshape-contents-body';
 export * from './utils/slash-command-parser';
 export * from './utils/webclient-factory';
+export * from './utils/required-scopes';