ci: set explicit read permissions on ci workflow

Set an explicit least-privilege permissions block so the workflow GITHUB_TOKEN is scoped to contents: read instead of inheriting the repository default.

Signed-off-by: Arpit Jain <arpitjain099@gmail.com>

Author: arpitjain099

.github/workflows/ci.yml

@@ -6,6 +6,9 @@ on:
       - main
   pull_request:
 
+permissions:
+  contents: read
+
 jobs:
   rubocop:
     name: Rubocop