chore(deps): update actions/stale action to v6

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
actions/stale	action	major	v5 -> v6

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Release Notes

actions/stale

### [`v6`](https://togithub.com/actions/stale/compare/v5...v6) [Compare Source](https://togithub.com/actions/stale/compare/v5...v6)

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