Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -13,7 +13,7 @@ build:
   stage: build
   script:
     - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
-    - docker pull $CI_REGISTRY_IMAGE:master
+    - docker pull $CI_REGISTRY_IMAGE:master || true
     - docker build --cache-from $CI_REGISTRY_IMAGE:master -t $IMAGE_TAG .
     - docker push $IMAGE_TAG