Update .gitlab-ci.yml file, using registry username and password

.gitlab-ci.yml

@@ -10,7 +10,7 @@ image_build:
   stage: build
   image: docker:stable
   before_script:
-    - docker login -u <username> -p <access_token> http://$CI_REGISTRY
+    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD http://$CI_REGISTRY
   script: |
     CI_COMMIT_SHA_7=$(echo $CI_COMMIT_SHA | cut -c1-7)
     docker build --tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA_7 .