fix build command

.gitlab-ci.yml

@@ -17,7 +17,7 @@ build:
   script:
     # use previous image as a cache to speedup build process
     - docker pull $CI_REGISTRY_IMAGE:latest || true
-    - docker build --cache-from $CI_REGISTRY_IMAGE:latest --tag $CI_REGISTRY_IMAGE:CI_COMMIT_SHORT_SHA .
+    - docker build --cache-from $CI_REGISTRY_IMAGE:latest --tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA .
 
 release:
   image: docker:20.10.16