Add trivy workflow permissions

Author: henrymcconville

.github/workflows/container-scan.yml

@@ -8,6 +8,11 @@ jobs:
   container-scan:
     name: Container Scan
     runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+      actions: read
+      contents: read
+
     steps:
       - name: Checkout code
         uses: actions/checkout@v4