Upgrade image for review cleanup

- fixes no method `#filter_map` which was added in Ruby 2.7.0

.gitlab/ci/review.gitlab-ci.yml

@@ -2,7 +2,7 @@ review-cleanup:
   extends:
     - .default-retry
     - .review:rules:review-cleanup
-  image: registry.gitlab.com/gitlab-org/gitlab-build-images:gitlab-helm3-kubectl1.14
+  image: registry.gitlab.com/gitlab-org/gitlab-build-images:gitlab-helm3.5-kubectl1.17
   stage: prepare
   environment:
     name: review/auto-cleanup