Specify github actions permissions (#172)

Author: maratori

.github/workflows/ci.yml

@@ -14,6 +14,9 @@ on:
   schedule:
     - cron: "0 0 * * 1" # Every Monday
 
+permissions:
+  contents: read
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true