Update deprecated CI_BUILD_* Variable

.gitlab-ci.yml

@@ -3,6 +3,6 @@ build_image:
   services:
     - docker:dind
   script:
-    - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY
+    - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
     - docker build -t $CI_REGISTRY_IMAGE --pull .
     - docker push $CI_REGISTRY_IMAGE