chg: update trigger to external_pull_request_event

Signed-off-by: Chenhan Yu <[email protected]>

Author: ChenhanYu

.gitlab/tests.yml

@@ -5,7 +5,7 @@
     - if: $JET_ONLY != null
       when: never
     - if: $CI_COMMIT_TAG =~ /^\d+\.\d+\.\d+$/
-    - if: $CI_PIPELINE_SOURCE == "web" || $CI_PIPELINE_SOURCE == "schedule"
+    - if: $CI_PIPELINE_SOURCE == "web" || $CI_PIPELINE_SOURCE == "external_pull_request_event"
 
 ##### Unit Tests #####
 unit: