chore(deps): update cachix/install-nix-action action to v21

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
cachix/install-nix-action	action	major	v20 -> v21

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Release Notes

cachix/install-nix-action

### [`v21`](https://togithub.com/cachix/install-nix-action/releases/tag/v21): install-nix-action-v21 [Compare Source](https://togithub.com/cachix/install-nix-action/compare/v20...v21) - pin Nix to 2.15.1 (recent releases broke too many things) - fix the action to work on custom containers

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Configuration

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[what-the-diff[bot]]

PR Summary

• Updated cachix/install-nix-action version The version of the cachix/install-nix-action was updated from v20 to v21, ensuring better performance and the use of the latest features.

[github-actions[bot]]

Since this pull request has not had any activity within the last 5 days, I have marked it as stale. I will close it if no further activity occurs within the next 5 days.

[renovate[bot]]

Renovate Ignore Notification

Because you closed this PR without merging, Renovate will ignore this update. You will not get PRs for any future 21.x releases. But if you manually upgrade to 21.x then Renovate will re-enable minor and patch updates automatically.

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