Define top level Permission for ci-schedule-compatibility workflow

Signed-off-by: aditya7302 <aditya7302@gmail.com>

.github/workflows/ci-schedule-compatibility.yaml

@@ -4,6 +4,9 @@ on:
     # Run this workflow "At 20:00 UTC on Sunday and Saturday"
     - cron: '0 20 * * 0,6'
 
+permissions:
+  contents: read # Required by actions/checkout to fetch the repository contents.
+
 jobs:
   e2e:
     name: e2e test