I think that I will never merge a PR without Code Review to get this badge but I've got it. In this post I will explain how to quickly get the badge.
All you need to create new project or use your existing project and make it Open Source. For this you need to add License file, you can do that via GitHub website. Add new file and name it LICENSE, LICENSE.md or LICENSE.txt and pick the license. But you need to make one important thing don't commit directly to master/main but create a PR. That PR you can merge without checking. This in turn will give you the badge.
If course you can use any edit to your own repo and use branch and PR strategy, instead of direct commit to master/main. But I think that adding a license will look cool when you inspect the badge and see what kind of PR it was.
I hope you like it, share in the comment if you successfully got the badge and follow me on Twitter @jcubic.