ci: permit stale workflow to delete cache

[Jefffrey]

Which issue does this PR close?

N/A

Rationale for this change

Some PRs are being omitted from stale check because they were in a cache, and the workflow appears to not have permission to delete cache so they are forever stuck as unprocessed.

For example in this run: https://github.com/apache/datafusion/actions/runs/24756695077/job/72431314533

Seeing this in logs:

[#20473]            issue skipped due being processed during the previous run
[#20460]            pull request skipped due being processed during the previous run
[#20448]            issue skipped due being processed during the previous run
[#20443]            issue skipped due being processed during the previous run
[#20435]            issue skipped due being processed during the previous run
[#20418]            issue skipped due being processed during the previous run
[#20417]            pull request skipped due being processed during the previous run
[#20416]            pull request skipped due being processed during the previous run
[#20403]            pull request skipped due being processed during the previous run

And at the end we see this warning:

Warning: Error delete _state: [403] Resource not accessible by integration - https://docs.github.com/rest/actions/cache#delete-github-actions-caches-for-a-repository-using-a-cache-key

stale workflow uses a cache in case it hits the operations-per-run limit meant to prevent API rate limiting (we have default of 30), so it seems we previously hit this limit and some issues/PRs were cached, and have never been uncached since so are never processed again. See: https://github.com/actions/stale#operations-per-run

What changes are included in this PR?

Give permission to stale workflow to run github actions (like delete cache). See recommended permissions:

https://github.com/actions/stale#recommended-permissions

Are these changes tested?

Are there any user-facing changes?

[Jefffrey]

Thanks @martin-g

[Jefffrey]

Before fix: https://github.com/apache/datafusion/actions/runs/24756695077/job/72431314533

After fix: https://github.com/apache/datafusion/actions/runs/24813042430/job/72621682281

• Warning gone, looks like cache successfully removed

We'll still need to wait for next run tomorrow before the previously cached PRs are finally reprocessed