FIX: use correct filename

.gitlab-ci.yml

@@ -167,7 +167,7 @@ test:
       - docker-compose -f .docker/docker-compose.yml down
 
         # Store mariadb image
-      - if [ ! -f ".gistlab-ci.yml" ]; then
+      - if [ ! -f "${MARIADBVERSION}.tar" ]; then
            time docker save $MARIADBVERSION > /image-cache/$MARIADBVERSION.tar || true;
         fi;