We discovered that the arm64 images were based on amd64 base images (#78) that went undiscovered as

1. We weren't running tests on arm64 — I wasn't aware that Travis supported arm64.
2. I was performing manual tests using Docker Desktop for M1 and Minikube, and Docker Desktop installs binfmt_exec extensions to allow non-native images.

We're also hitting frequent rate limiting issues with Docker Hub on Travis. Since Github Actions supports builds in amd64 and arm64, so we should run tests there.