Vagrant version issue with git bash

I am trying to vargrant up in my laravel project. when i run the command 'vagrant up' it shows me the error and i am using the latest version of git bash (version 2.18.0) and vagrant(2.1.2). I'm using the latest version the git bash then how it update it. please help me to solve this issue.

   Bringing machine 'laravel-api' up with 'virtualbox' provider...
   The version of powershell currently installed on this host is less than
   the required minimum version. Please upgrade the installed version of
   powershell to the minimum required version and run the command again.

   Installed version: 2

   Minimum required version: 3

via Chebli Mohamed