build(deps): bump cachix/install-nix-action from V28 to 29

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from V28 to 29. This release includes the previously tagged commit.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@V28...v29)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
...

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

Author: dependabot[bot]

.github/workflows/build.yml

@@ -42,7 +42,7 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v4
     - name: Install nix
-      uses: cachix/install-nix-action@V28
+      uses: cachix/install-nix-action@v29
       with:
         nix_path: "${{ matrix.nixPath }}"
         extra_nix_config: |

.github/workflows/test.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v4
     - name: Install nix
-      uses: cachix/install-nix-action@V28
+      uses: cachix/install-nix-action@v29
       with:
         nix_path: "${{ matrix.nixPath }}"
         extra_nix_config: |