CI: Pull in config as published via 'main'

.gitlab-ci.yml

@@ -2,6 +2,7 @@
 stages:
   - static
   - test
+  - build
 
 cache:
   paths:
@@ -48,15 +49,25 @@ codespell:
     - codespell -q 2 -f -I utils/ci/codespell/ignored_words.txt -S turing-questions.yml,de.yml,es.yml,vendor
   stage: static
 
-ruby:2.4:
-  image: ruby:2.4
-  <<: *test_ruby
 ruby:2.5:
   image: ruby:2.5
   <<: *test_ruby
 ruby:2.6:
   image: ruby:2.6
   <<: *test_ruby
+ruby:2.7:
+  image: ruby:2.7
+  <<: *test_ruby
+ruby:3.0:
+  image: ruby:3.0
+  <<: *test_ruby
+
+build-container-image:
+  image: registry.0xacab.org/schleuder/schleuder-ci-images:debian-container-tools
+  only:
+    - master
+  script: sh -x utils/buildah.sh
+  stage: build
 
 bundler:audit:
   image: ruby:2.5