Bump cachix/install-nix-action from 27 to 29

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 27 to 29.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@ba0dd84...9f70348)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/deadnix.yml

@@ -13,7 +13,7 @@ jobs:
           egress-policy: audit
 
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
-      - uses: cachix/install-nix-action@ba0dd844c9180cbf77aa72a116d6fbc515d0e87b # V27
+      - uses: cachix/install-nix-action@9f70348d77d0422624097c4b7a75563948901306 # V29
       - uses: cachix/cachix-action@ad2ddac53f961de1989924296a1f236fcfbaa4fc # v15
         with:
           name: deadnix

.github/workflows/deploy-server.yml

@@ -50,7 +50,7 @@ jobs:
           fetch-depth: 0
 
       - name: Install nix
-        uses: cachix/install-nix-action@ba0dd844c9180cbf77aa72a116d6fbc515d0e87b # V27
+        uses: cachix/install-nix-action@9f70348d77d0422624097c4b7a75563948901306 # V29
         with:
           nix_path: nixpkgs=channel:nixos-24.05
 

.github/workflows/update-and-deploy-server.yml

@@ -36,7 +36,7 @@ jobs:
         run: echo "previous_hash=$(git rev-parse HEAD)" >> "$GITHUB_OUTPUT"
 
       - name: Install nix
-        uses: cachix/install-nix-action@ba0dd844c9180cbf77aa72a116d6fbc515d0e87b # V27
+        uses: cachix/install-nix-action@9f70348d77d0422624097c4b7a75563948901306 # V29
 
       - name: Update flake lock file
         run: nix flake update --no-warn-dirty