Add a Github Actions to label Bitmoji PR's

[asg017]

A Github Action is a feature where you can kickoff an action whenever an event happens in a Github repository. For example, you can set up an action that will send a message in Discord to someone whenever a new Pull Request is made, or run tests on a code whenever someone pushes to a repo.

For this repository, most PR's come from someone adding their bitmoji by adding a name.json file to the /bitmojis directory. I think it would be awesome if we could automatically label those PR's with a Github label called new-bitmoji (or something).

Thankfully, Github has an example Action that does this: https://github.com/actions/labeler

So, someone would have to do this:

1. Fork this repository
2. Using the example in the actions/labeler repo linked above, add a "workflow" (e.g. .github/workflows/labeler.yml) to your forked repository.
3. (optional) Test it in your forked repo. On github, create a new file in /bitmojis, and choose "create a pull request" when prompted (instead of merging directly to master). Hopefully, when you make the PR, your Github Action/workflow should have been kicked off, and a label should be added to that PR
4. Once it looks good on your repo, send a PR from your forked repo to this repo (os-ucsd/bitmoji).
5. We can merge it in, and it should work out! 🎉

If this is confusing at all, or if you get stuck or need to debug with someone, feel free to comment below/reach out to me on discord!

[asg017]

Also, some context as to why we want this - on top of this, we can set it up so that maintainers can get a message everytime there's a PR with a specific label. That way, we don't accidentally forget to merge someone's PR, or avoid using having to manually check for new PRs every so often