I literally couldn't find anything like this, it's probably just me being bad though.
Made something better? Fork the repository and submit a pull request!
npm install
nano main.js and modify stuff from the config var to your likings, everything else can stay default.
nodejs main.js to run the bot.
Add a new Web Hook to whatever repository you want to track, with the bot's URL, e.g http://getrektby.us:4021/git.json
Enjoy an influx of spam as people commit to the repository!