Also build arm images (#58)

Based on https://www.docker.com/blog/multi-arch-build-and-images-the-simple-way/
https://github.com/docker/build-push-action and https://docs.docker.com/engine/reference/commandline/buildx_build/#platform

.github/workflows/docker-hub-develop.yml

@@ -9,7 +9,7 @@ on:
 
 env:
   DOCKER_NAMESPACE: gnuxie
-  PLATFORMS: linux/amd64
+  PLATFORMS: linux/amd64,linux/arm64
   # Only push if this is main, otherwise we just want to build
   PUSH: ${{ github.ref == 'refs/heads/main' }}
 

.github/workflows/docker-hub-release.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   DOCKER_NAMESPACE: gnuxie
-  PLATFORMS: linux/amd64
+  PLATFORMS: linux/amd64,linux/arm64
 
 jobs:
   docker-release: