fix: add contents:read permission to system-tests workflow call

Author: nccatoni

.github/workflows/dev.yml

@@ -201,6 +201,7 @@ jobs:
     secrets:
       TEST_OPTIMIZATION_API_KEY: ${{ secrets.DD_CI_VIS_API_KEY }}
     permissions:
+      contents: read
       id-token: write
     with:
       library: cpp