Potential fix for code scanning alert no. 4: Workflow does not contain permissions

[nicolasbock]

Potential fix for https://github.com/nicolasbock/ebuildtester/security/code-scanning/4

To fix the flagged issue, add a permissions block to the workflow to explicitly define the permissions for the GITHUB_TOKEN. Since the workflow primarily checks out code, builds, tests, and archives artifacts, the least privilege permissions required are likely contents: read (for reading the repository contents) and possibly write permissions for actions if artifact uploads are required.

The permissions block can be added globally at the workflow level, so it applies to all jobs. Alternatively, it can be added to specific jobs if different permissions are required for each job. In this case, we will add the permissions block globally for simplicity and clarity.

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Pull Request Overview

Adds explicit permissions to the GitHub Actions workflow to satisfy the code scanning requirement for least-privilege GITHUB_TOKEN usage.

• Introduces a global permissions block with contents: read and actions: write.
• Applies permissions at the workflow level for simplicity.