Update actions/stale action to v8

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
actions/stale	action	major	v7 -> v8

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Release Notes

actions/stale

### [`v8`](https://togithub.com/actions/stale/compare/v7...v8) [Compare Source](https://togithub.com/actions/stale/compare/v7...v8)

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[kitchen-porter]

Released as: 6.0.3