title: How to upgrade Vue version
body: <p>I was using the Vue version (2.5), I ran that command <code>npm install -g @vue/cli</code> after that I check my vue version by using the command <code>vue --version</code>and it shows me <code>@vue/cli 4.1.2</code>. but in my package.json file the version did not upgrade, it still showing me the older version i.e 2.5.7. 
  <a href="https://i.stack.imgur.com/cKW6d.png" rel="noreferrer"><img src="https://i.stack.imgur.com/cKW6d.png" alt="enter image description here"></a> </p>
  
  <p>Any help would be highly appreciable</p>