Update .gitlab-ci.yml file

.gitlab-ci.yml

@@ -23,6 +23,7 @@ stages:
 variables:
   DOCKER_HOST: tcp://docker:2375
   DOCKER_TLS_CERTDIR: ""
+  DOCKER_BUILDKIT: 1
 
 build-docker-image:
   image: docker:latest
@@ -55,4 +56,4 @@ deploy-to-bw-cloud:
       docker run -d --name flask-container -p 5001:5000 $DOCKER_REPO/$PROJECT:$CI_COMMIT_REF_SLUG
       "
   only:
-    - main
+    - main
\ No newline at end of file