Remove scheduled releases

The action will be released roughly every two weeks along
with the CodeQL CLI release process.

Author: aeisenberg

.github/workflows/update-release-branch.yml

@@ -1,7 +1,5 @@
 name: Update release branch
 on:
-  schedule:
-    - cron: 0 9 * * 1
   repository_dispatch:
     # Example of how to trigger this:
     # curl -H "Authorization: Bearer <token>" -X POST https://api.github.com/repos/github/codeql-action/dispatches -d '{"event_type":"update-release-branch"}'