Potential fix for code scanning alert no. 28: Workflow does not contain permissions

[teolemon]

Potential fix for https://github.com/openfoodfacts/openfoodfacts-web/security/code-scanning/28

To address this, add a permissions block to the workflow, ensuring that the minimal required GitHub token permissions are set. Since the Crowdin action opens pull requests, we need pull-requests: write and, since it interacts with repository contents, contents: read. From best practices, it's recommended to add permissions at the workflow root to cover all jobs unless specific jobs need elevating. Insert the following block after the name: line (before on:):

permissions:
  contents: read
  pull-requests: write

No imports, methods, or further definitions are necessary. The relevant code region to change is before the on: key.

---

Suggested fixes powered by Copilot Autofix. Review carefully before merging.