How Can I Serve Robots.txt On An SPA Using React With Firebase Hosting?

I have an SPA built using create-react-app and wish to have a robots.txt like this:

http://example.com/robots.txt

I see on this page that:

You need to make sure your server is configured to catch any URL after it's configured to serve from a directory.

But for firebase hosting, I'm not sure what to do.

Just add the following rules to the "rewrites" section in firebase.json

"rewrites": [
      {
        "source": "/robots.txt",
        "destination": "/robots.txt"
      },
      {
        "source": "**",
        "destination": "/index.html"
      }
]