set multi-arch docker build in ACR github action

Author: kelsey-wong

.github/workflows/build-push-image-acr.yml

@@ -59,6 +59,7 @@ jobs:
               uses: docker/build-push-action@v6
               with:
                 push: true
+                platforms: linux/amd64,linux/arm64
                 tags: ${{ steps.set-variables.outputs.image_tags }}
                 context: ${{ inputs.context }}
                 target: hosted