Only run pipelines in the main repo

.gitlab-ci.yml

+workflow:
+  rules:
+    # only run when on the main repo
+    - if: '$CI_PROJECT_ID == "3528"'
+      when: always
+
 .official-releases:
   rules:
     - if: $CI_COMMIT_TAG =~ /\A\d+\.\d+\.\d+\z/