[ci] pipeline rules for benchmark tests

.gitlab-ci.yml

 image: rocker/tidyverse
 
+stages:
+    - test
+    - benchmark-test
+
 test:
   stage: test
   tags:
@@ -28,5 +32,15 @@ test:
       - "$RETICULATE_MINICONDA_PATH"
       - "$RETICULATE_PYTHON_ENV"
   # script will only run then attempting to merge/push to master
-  only:
-    - merge_requests
\ No newline at end of file
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+    - if: '$CI_PIPELINE_SOURCE == "api"'
+
+benchmark-test:
+  stage: benchmark-test
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "api"'
+      when: on_success
+  script:
+    - echo Hello World
+