Update cachix/install-nix-action action to v29

Author: renovate[bot]

.github/workflows/deploy.yaml

@@ -11,7 +11,7 @@ jobs:
     steps:
 
     - uses: actions/checkout@v4.1.7
-    - uses: cachix/install-nix-action@v27
+    - uses: cachix/install-nix-action@v29
       with:
         install_url: https://nixos-nix-install-tests.cachix.org/serve/i6laym9jw3wg9mw6ncyrk6gjx4l34vvx/install
         install_options: '--tarball-url-prefix https://nixos-nix-install-tests.cachix.org/serve'