Potential fix for code scanning alert no. 20: Workflow does not contain permissions

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

Author: tdruez

.github/workflows/run-unit-tests-docker.yml

@@ -2,6 +2,9 @@ name: Run unit tests on Docker container
 
 on: [push, pull_request]
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-24.04