Update cachix/install-nix-action action to v25

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
cachix/install-nix-action	action	major	v24 -> v25

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Release Notes

cachix/install-nix-action (cachix/install-nix-action)

### [`v25`](https://togithub.com/cachix/install-nix-action/releases/tag/v25): install-nix-action-v25 [Compare Source](https://togithub.com/cachix/install-nix-action/compare/v24...v25) Nix 2.19.2

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Configuration

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🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

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