Fix image digest determination in .gitlab-ci.yml

Author: yunus-qureshi

.gitlab-ci.yml

@@ -7,7 +7,7 @@ build-operator:
     - echo $CI_COMMIT_TAG
     - make docker-build IMG="$IMAGE"
     - docker push "$IMAGE"
-    - newimage=$(docker inspect $IMAGE | python -c 'import json,sys; print(json.load(sys.stdin)[0]["RepoDigests"][0])')
+    - newimage=$DOCKER_REPO@$(skopeo inspect docker://$IMAGE |  jq -r .Digest)
     - echo $newimage
     - docker rmi "$IMAGE" && docker system prune -f
     - make operator-yaml IMG=$newimage