fix update thread error

src/components/thread/EditThread.jsx

 import axios from 'axios';
 import React, { useState, useEffect } from 'react';
 import { useInput } from '../../helpers/hooks/input-hook';
-import authHeader from '../../helpers/services/auth.service';
+import { authHeader } from '../../helpers/services/auth.service';
 import { API_URL } from '../../config/keys';
 import '../../styles/thread/Form.css';