ci: add commitlint to ci checks for merge requests

.gitlab-ci.yml

@@ -3,7 +3,13 @@
 #
 # SPDX-License-Identifier: MIT
 
-image: node:lts
+workflow:
+    rules:
+        - if: $CI_PIPELINE_SOURCE == "merge_request_event"
+        - if: $CI_COMMIT_BRANCH && $CI_OPEN_MERGE_REQUESTS
+          when: never
+        - if: $CI_COMMIT_BRANCH
+        - if: $CI_COMMIT_TAG
 
 variables:
     PACKAGE_NAME: ds4
@@ -17,6 +23,8 @@ stages:
     - release
     - publish
 
+image: node:lts
+
 cache: &global_cache
     paths:
         - .yarn/cache
@@ -61,6 +69,15 @@ reuse:
     script:
         - reuse lint
 
+commitlint:
+    stage: check
+    before_script:
+        - yarn install --immutable
+    script:
+        - yarn run commitlint --from $CI_MERGE_REQUEST_DIFF_BASE_SHA
+    rules:
+        - if: "$CI_PIPELINE_SOURCE == 'merge_request_event' && $CI_MERGE_REQUEST_DIFF_BASE_SHA"
+
 build:
     stage: build
     before_script: