chore(ci-deps): bump the gh-actions-deps group with 1 update (#31)

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


Updates `cachix/install-nix-action` from 25 to 26
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@v25...v26)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci-tests-nix.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
       - name: Checkout sources
         uses: actions/checkout@v4
-      - uses: cachix/install-nix-action@v25
+      - uses: cachix/install-nix-action@v26
       - name: Build Nix package
         run: nix build
       - name: Check Flake formatting