Update publish conditions.

.github/workflows/pub_staging_push_event.yml

@@ -1,7 +1,7 @@
-name: Publish Staging Pull Request
+name: Publish Staging Push Event
 on:
   workflow_dispatch:
-  pull_request:
+  push:
     branches:
       - staging
 
@@ -16,4 +16,4 @@ jobs:
             -H "Accept: application/vnd.github.v3+json" \
             -H "Authorization: token ${{ secrets.TRIGGER_PUBLISH_STAGING_PR_TOKEN }}" \
             https://api.github.com/repos/awalsh128/cache-apt-pkgs-action-ci/dispatches \
-            -d '{"event_type":"staging_pull_request"}'
+            -d '{"event_type":"staging_push"}'