Potential fix for code scanning alert no. 10: Workflow does not contain permissions

[abelcheung]

Potential fix for https://github.com/abelcheung/types-lxml/security/code-scanning/10

In general, the fix is to explicitly set a permissions block at the workflow level (applies to all jobs) or per job, restricting the GITHUB_TOKEN to the minimal scopes needed. For this workflow, the jobs only need to interact with actions artifacts; they don't push commits or manage issues/PRs. Thus we can safely set permissions: contents: read at the workflow root as a conservative baseline (the minimum GitHub recommends for most workflows) while leaving the existing actions: write permission on the log-aggregation job, which is already explicitly configured for cleaning up artifacts.

The single best fix without changing functionality is:

• Add a workflow-level permissions block just after the name: line.
• Set contents: read there, which is sufficient for typical artifact operations and avoids unnecessary write privileges.
• Keep the existing permissions on the log-aggregation job as-is, since it explicitly needs actions: write for geekyeggo/delete-artifact@v5.

All required changes are confined to .github/workflows/test_inc.yml, and no imports or additional methods are involved since this is a YAML configuration change only.

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