Like it says, it's a docker image built on alpine with curl installed. Size 5.93 MB.
Available from docker hub as byrnedo/alpine-curl
Alpine versions: 3.16, 3.17, 3.18, 3.19
Note: this repo has a github actions scheduled build nightly to keep up with the alpine base image. So there should be fresh images on docker hub even without commits here.
docker run --rm byrnedo/alpine-curl https://www.google.com