composer/plugin/drupal-config#2 Add CI config

.gitlab-ci.yml

+include:
+  - project: gitlab-ci-cd/general
+    ref: main
+    file: '/mixins.yml'
+
+Publish Release:
+  extends: '.merge'
+  variables:
+    SOURCE_BRANCH: develop
+  rules:
+    - if: $SKIP_PUBLISH_RELEASE == "1"
+      when: never
+    - if: $CI_COMMIT_BRANCH == "develop"