Only run lint jobs for MRs

.gitlab-ci.yml

@@ -127,7 +127,8 @@ black:
     - pip install black
   script:
     - black --check --diff .
-  only:
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
       changes:
         - api/**/*
 
@@ -145,7 +146,8 @@ flake8:
     key: "$CI_PROJECT_ID__flake8_pip_cache"
     paths:
       - "$PIP_CACHE_DIR"
-  only:
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
       changes:
         - api/**/*
 
@@ -164,7 +166,8 @@ eslint:
     key: "$CI_PROJECT_ID__eslint_npm_cache"
     paths:
       - front/node_modules
-  only:
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
       changes:
         - front/**/*