Update ts/flow types

CompletionHandler is no longer passed as a param to listener.
Instead it exists on the IOSNotification class.

src/index.d.ts

@@ -1168,7 +1168,7 @@ declare module 'react-native-firebase' {
         ): () => any;
 
         onNotificationDisplayed(
-          listener: (notification: Notification, done: CompletionHandler) => any
+          listener: (notification: Notification) => any
         ): () => any;
 
         onNotificationOpened(
@@ -1473,6 +1473,7 @@ declare module 'react-native-firebase' {
         hasAction?: boolean;
         launchImage?: string;
         threadIdentifier?: string;
+        complete?: CompletionHandler;
 
         addAttachment(
           identifier: string,

src/modules/notifications/index.js

@@ -12,9 +12,7 @@ import AndroidAction from './AndroidAction';
 import AndroidChannel from './AndroidChannel';
 import AndroidChannelGroup from './AndroidChannelGroup';
 import AndroidNotifications from './AndroidNotifications';
-import IOSNotifications, {
-  type BackgroundFetchResultValue,
-} from './IOSNotifications';
+import IOSNotifications from './IOSNotifications';
 import AndroidRemoteInput from './AndroidRemoteInput';
 import Notification from './Notification';
 import {
@@ -36,9 +34,7 @@ import type {
   Schedule,
 } from './types';
 
-type CompletionHandler = BackgroundFetchResultValue => void;
-
-type OnNotification = (Notification, CompletionHandler) => any;
+type OnNotification = Notification => any;
 
 type OnNotificationObserver = {
   next: OnNotification,