Set up multi-arch builds

.gitlab-ci.yml

@@ -25,9 +25,11 @@ Build:
   stage: build
   script:
     - docker pull $CI_HUB_USERNAME/$CI_PROJECT_NAME:latest || true
+    - docker buildx create --use
     - >
-      docker build
+      docker buildx build
       --pull
+      --platform linux/amd64,linux/arm64
       --cache-from $CI_HUB_USERNAME/$CI_PROJECT_NAME:latest
       --tag $CI_HUB_USERNAME/$CI_PROJECT_NAME:$CI_COMMIT_SHORT_SHA
       .