chore: migrate redux-thunk to v4

admin/src/helpers/configureStore.js

@@ -1,5 +1,5 @@
 import { createStore, applyMiddleware, compose } from 'redux';
-import thunkMiddleware from 'redux-thunk';
+import { thunk } from 'redux-thunk';
 import { Map } from 'immutable';
 
 import rootReducer from '../state/reducers';
@@ -10,7 +10,7 @@ const configureStore = () => {
 
   const enhancers = [];
   const middlewares = [
-    thunkMiddleware,
+    thunk,
   ];
 
   let devtools;