Potential fix for code scanning alert no. 3220: Workflow does not contain permissions

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

.github/workflows/trivy.yaml

@@ -1,5 +1,7 @@
 name: Security Scan
 on: [pull_request, workflow_dispatch]
+permissions:
+  contents: read
 jobs:
   scan:
     runs-on: ubuntu-latest