Add workflow rules for Git Flow

.gitlab-ci.yml

+workflow:
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
+    - if: $CI_PIPELINE_SOURCE == "schedule"
+    - if: $CI_COMMIT_TAG
+    - if: $CI_COMMIT_REF_PROTECTED == "true"
+
 include: 
   - local: tests/unit.gitlab-ci.yml
   - local: tests/integration.gitlab-ci.yml