Update .gitlab-ci.yml file

.gitlab-ci.yml

 build:
   stage: build
   image: docker:latest
-  services:
-    - docker:dind
+  variables:
+    DOCKER_BUILDKIT: 1
   before_script:
     - docker info
     - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY