FIX: used wrong branch name in docker image reference

.gitlab-ci.yml

@@ -73,7 +73,7 @@ test:
     entrypoint: ["/bin/sh", "-c"]
   script:
       - if [[ "$CAOSDB_TAG" == "" ]]; then
-            CAOSDB_TAG=dev-latest;
+            CAOSDB_TAG=master-latest;
         fi
       - echo $CAOSDB_TAG
       - docker login -u testuser -p $CI_REGISTRY_PASSWORD $CI_REGISTRY