Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -3,13 +3,7 @@ image: docker:latest
 services:
   - docker:dind
 
-stages:
-  - build
-
-variables:
-  TEST_IMAGE_NAME: grav_test:$CI_COMMIT_REF_NAME
-
 build:
   stage: build
   script:
-    - docker build --pull -t $TEST_IMAGE_NAME .
+    - docker build --pull -t grav_test .