Simplify useEffectEvent types

Author: eps1lon

packages/react-reconciler/src/ReactInternalTypes.js

@@ -383,7 +383,7 @@ export type Dispatcher = {
     create: () => (() => void) | void,
     deps: Array<mixed> | void | null,
   ): void,
-  useEffectEvent?: <Args, Return, F: (...Array<Args>) => Return>(
+  useEffectEvent?: <Args, F: (...Array<Args>) => mixed>(
     callback: F,
   ) => F,
   useInsertionEffect(

packages/react/src/ReactHooks.js

@@ -234,7 +234,7 @@ export function useMemoCache(size: number): Array<any> {
   return dispatcher.useMemoCache(size);
 }
 
-export function useEffectEvent<Args, Return, F: (...Array<Args>) => Return>(
+export function useEffectEvent<Args, F: (...Array<Args>) => mixed>(
   callback: F,
 ): F {
   const dispatcher = resolveDispatcher();