stale: enable cache

[ericLemanissier]

only 30 PRs are processed per day, so cache is needed to keep state and continue from the last PRs of the last days.

fixes error https://github.com/conan-io/conan-center-index/actions/runs/7810903828/job/21305055330#step:2:1032

state: persisting info about 250 issue(s)
Warning: Error delete _state: [403] Resource not accessible by integration
/usr/bin/tar --posix -cf cache.tzst --exclude cache.tzst -P -C /home/runner/work/conan-center-index/conan-center-index --files-from manifest.txt --use-compress-program zstdmt
Failed to save: Unable to reserve cache with key _state, another job may be creating this cache. More details: Cache already exists. Scope: refs/heads/master, Key: _state, Version: fa41d75081481069cfb6b92a5f83a94c6e06ef3ab2e6b762649ac5f86f46153f

cf actions/stale#1090 (comment)

---

• I've read the contributing guidelines.
• I've used a recent Conan client version close to the currently deployed.
• I've tried at least one configuration locally with the conan-center hook activated.

[github-actions]

🤖 Beep Boop! This pull request is making changes to '.github//'.

👋 @ericLemanissier @Croydon you might be interested. 😉

[ericLemanissier]

AFAIU, the error happens on this line because the DELETE verb on an action cache needs actions:write to use this endpoint : https://docs.github.com/en/rest/actions/cache?apiVersion=2022-11-28#delete-github-actions-caches-for-a-repository-using-a-cache-key

[uilianries]

I'm not happy with this change, because it will give a whole write access. A second option would be running all PRs, but we have +600 now and it would reach out Github API rate limit.

On the other hand, this is an official Action maintained by Github, so I only fell safe because of this.

Still, I prefer waiting for actions/stale#1133, because more projects are affected because of this problem.

[ericLemanissier]

To be clear, it gives write access only to the endpoints listed in this "Actions" section: https://docs.github.com/en/rest/authentication/permissions-required-for-fine-grained-personal-access-tokens?apiVersion=2022-11-28#repository-permissions-for-actions, not full write access to everything in the repo.

I think we could process more PRs per run. AFAIU, operations are consumed only when pull requests are marked stale or closed. according to https://github.com/conan-io/conan-center-index/actions/runs/7810903828/job/21305055330#step:2:480, marking a PR stales costs 4 operations, and each batch of 100 PRs/issues inspected costs one operation. This means that we will in term still process all PRs even without cache.
According to this log, we have 15000 operations granted by github

[uilianries]

@ericLemanissier Yes, I read the documentation. Still, the author is aware about and more repositories are being affected. I would prefer waiting for a real fix than trying a workaround which would give more permissions now. Thank you for giving more context about the situation.