gitlab-ci: add yamllint job

.gitlab-ci.yml

@@ -274,6 +274,35 @@ safety:
     - python3 -m safety --key "$SAFETY_API_KEY" --stage cicd scan
 
 
+# TODO tests/*/*/*.yaml are not covered
+yamllint:
+  image: debian:bookworm-slim
+  rules:
+    # once only:/changes: are ported to rules:, this could be removed:
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
+      when: never
+    - if: $CI_PIPELINE_SOURCE == "push"
+      changes:
+        - .gitlab-ci.yml
+        - .safety-policy.yml
+        - .yamllint
+        - tests/*.yml
+        - tests/*/*.yml
+        - tests/*/*/.*.yml
+  <<: *apt-template
+  variables:
+    LANG: C.UTF-8
+  script:
+    - apt-get install yamllint
+    - yamllint
+        .gitlab-ci.yml
+        .safety-policy.yml
+        .yamllint
+        tests/*.yml
+        tests/*/*.yml
+        tests/*/*/.*.yml
+
+
 # Run all the various linters and static analysis tools.
 locales:
   image: debian:bookworm-slim