ci(deps): bump cachix/install-nix-action

Bumps the github-actions group with 1 update in the / directory: [cachix/install-nix-action](https://github.com/cachix/install-nix-action).


Updates `cachix/install-nix-action` from 25 to 31
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Changelog](https://github.com/cachix/install-nix-action/blob/master/RELEASE.md)
- [Commits](cachix/install-nix-action@v25...v31)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-version: '31'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         uses: jdx/mise-action@v4
 
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable
           extra_nix_config: |