Auto-Assign Github Action

[ashishnagpal2498]

Add auto-assign github action to the project.
This will allow mentors/ project admins to review the pull request at same instant it is requested.
Functionality

1. Create a group of project admins and mentors separately.
2. Each pull request should be auto-assign to a mentor and project Admin.
   Reference - https://github.com/kentaro-m/auto-assign

[vsasvipul0605]

assign this issue to me.