Update @koa/cors to allow credential as a function (#54636)
Update @koa/cors to allow credential as a function (#54636)

From the @koa/cors [README](https://github.com/koajs/cors):

```
 *  - {Boolean|Function(ctx)} credentials `Access-Control-Allow-Credentials`, default is false.
```
markogresak/DefinitelyTyped