Strange email from unknown company

I am using Version 10.0.17763 Build 17763

I have received a "no reply" email from a company called GitHub telling me that I am using GitHub and that my password is weak and that I should visit their site and create a stronger password. It also tells me that if I don't change my password I will no longer be able to use GitHub.

I have never even heard of this company. Googling it confused me no end. Can anyone give me an idea how I am using this company? Is it part of some other software? I have been using the same software for a long time and this is the first time I have heard of this company. I do not have cloud storage of any kind (if that is of any consequence). I'm not tech-savvy, obviously.

I am posting in this section because I don't know what the software is, or where else to post. I thank one and all in advance for all assistance understanding this issue.

I'm the OP.

A question comes to mind: If I were using GitHub for something (they say I am using it) wouldn't the word "github" show up somewhere in Task Manager? Well, it doesn't. Another thing: Some 25 years ago I bought a notebook where I write down all my passwords. I do not keep the notebook near the computer. Whenever I change a password, I do not erase the old one, I write "old" next to it and then write in the new one. The word github appears nowhere in the notebook. Yes, paper note book, written by hand, with my 50 year old Parker fountain pen, same as I used at uni when the world was young.

Thank you Compumind and Dalchina for being so kind and patient. I think I shall adopt the suggestion "don't worry, delete it". I shall also mark the post solved and hope for the best.

I take this opportunity to wish one and all the very best of health and prosperity for the holidays and beyond.