added a stage to trigger cb pipeline

.gitlab-ci.yml

 stages:
   - test
   - deploy
+  - trigger
 
 test:
    stage: test
@@ -21,3 +22,9 @@ deploy_uniformgrid_gpu:
     - pip install --user .
     - python3 dashboards/deploy.py
   when: manual
+
+trigger_cb_pipeline:
+  stage: trigger
+  script:
+    - 'curl --fail --request POST --form token=$CB_TRIGGER_TOKEN --form ref=master "$CB_TRIGGER_API_URL"'
+  when: manual