Potential fix for code scanning alert no. 12: Workflow does not contain permissions

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

Author: oetr

.github/workflows/run-all-tests-main.yaml

@@ -3,6 +3,8 @@ on:
   push:
     branches: [main]
   workflow_dispatch:
+permissions:
+  contents: read
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true