chore(deps): update cachix/install-nix-action action to v20

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
cachix/install-nix-action	action	major	v19 -> v20

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Release Notes

cachix/install-nix-action

### [`v20`](https://togithub.com/cachix/install-nix-action/releases/tag/v20): install-nix-action-v20 [Compare Source](https://togithub.com/cachix/install-nix-action/compare/v19...v20) https://discourse.nixos.org/t/nix-2-14-0-released/25900/4Fix support for Nix 2.14 new profile location: [https://github.com/NixOS/nix/pull/5226](https://togithub.com/NixOS/nix/pull/5226)

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Configuration

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[what-the-diff[bot]]

• The version of the cachix/install-nix-action was updated from v19 to v20.