add workflow rule to prevent duplicated pipelines

.gitlab-ci.yml

@@ -2,6 +2,14 @@ variables:
   SECURE_ANALYZERS_PREFIX: registry.gitlab.com/gitlab-org/security-products/analyzers
   DOCKER_IMAGE_SHA: ${CI_REGISTRY_IMAGE}:${CI_COMMIT_SHA}
 
+workflow:
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+    - if: '$CI_PIPELINE_SOURCE == "schedule"'
+    - if: '$CI_COMMIT_BRANCH && $CI_OPEN_MERGE_REQUESTS && $CI_PIPELINE_SOURCE == "push"'
+      when: never
+    - if: '$CI_COMMIT_BRANCH'
+
 stages:
   - .pre
   - test