chore: support building multi-platform image

Author: lalver1

.github/workflows/docker-publish.yml

@@ -64,13 +64,17 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
       - name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v3
 
       - name: Build, tag, and push image to GitHub Container Registry
         uses: docker/build-push-action@v6
         with:
+          platforms: linux/amd64,linux/arm64
           builder: ${{ steps.buildx.outputs.name }}
           build-args: GIT-SHA=${{ github.sha }}
           cache-from: type=gha,scope=cal-itp