Updated triggers for workflow check-api-outdated

Author: ckunki

.github/workflows/check-api-outdated.yml

@@ -5,10 +5,6 @@ on:
     branches-ignore:
       - "github-pages/*"
       - "gh-pages/*"
-      - "main"
-      - "master"
-  pull_request:
-    types: [opened, reopened]
   workflow_dispatch:
   schedule:
     # “At 4 am on every day.” (https://crontab.guru)