ci: re-enable MR push triggered pipeline

.gitlab-ci.yml

@@ -9,14 +9,9 @@ stages:
   - deploy
   - post_deploy
 
-# pipelines will not be created in such two cases:
-# 1. MR push
-# 2. push not on "master/release" branches, and not tagged
-# This behavior could be changed after the `rules: changes` feature is implemented
 workflow:
   rules:
-    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
-      when: never
+    # Disable those non-protected push triggered pipelines
     - if: '$CI_COMMIT_REF_NAME != "master" && $CI_COMMIT_BRANCH !~ /^release\/v/ && $CI_COMMIT_TAG !~ /^v\d+\.\d+(\.\d+)?($|-)/ && $CI_PIPELINE_SOURCE == "push"'
       when: never
     - when: always