I hire a lot of programmers for tiny tasks. I very clearly specify that the tasks can only be completed by making a pull request on GitHub. Unfortunatelly, so many programmers do not know Git and often the programmers cannot complete the project due to not understanding/being willing to learn Git, even after they have undertaken the programming of the task. This is bad both for me and for the programmers. Sometimes I end up arguing for why it is inefficient that they just send me a zip file containing the code.

Therefore, I am looking for an online service to certify that the programmers know how to make a pull request so I do not waste their nor my time. The certificate should be free for the coders, but may cost me. It is important that the course just focuses on exactly what is needed to make a clean pull request so it should not take more than 5 minutes to go through.

Does such a thing exist?