drone notify-gogs event fix when pull_reqyest

.drone.yml

@@ -39,8 +39,8 @@ pipeline:
   notify-gogs:
     image: golang
     when:
-      event: pull-request
+      event: pull_request
     secrets: [BUILDBOT]
     commands:
       - echo "Notifying"
-      - sh gogs-notify.sh
+      - sh gogs-notify.sh