message: imp(core): updated type declaration for use operator
diff: import { Observable, of } from 'rxjs';
  import { mergeMap } from 'rxjs/operators';
  +import { EffectMetadata } from '../../effects/effects.interface';
  interface MiddlewareLike<I, O> {
  (i$: Observable<I>, client: any, meta: any): Observable<O>;
  }
  export const use = <I, O>
  - (middleware: MiddlewareLike<I, O>, client?: any, meta?: any) =>
  + (middleware: MiddlewareLike<I, O>, client?: any, meta?: EffectMetadata) =>
  (source$: Observable<I>) =>
  source$.pipe(
  mergeMap(req => middleware(of(req), client!, meta!) as Observable<O>)
  