build(deps): bump cachix/install-nix-action from v11 to v12

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from v11 to v12.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](https://github.com/cachix/install-nix-action/compare/v11...07da2520eebede906fbeefa9dd0a2b635323909d)

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

.github/workflows/build.yml

@@ -38,7 +38,7 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2.3.4
     - name: Install nix
-      uses: cachix/install-nix-action@v11
+      uses: cachix/install-nix-action@v12
       with:
         nix_path: "${{ matrix.nixPath }}"
     - name: Show nixpkgs version