build(deps): bump cachix/cachix-action from 15 to 16

Bumps [cachix/cachix-action](https://github.com/cachix/cachix-action) from 15 to 16.
- [Release notes](https://github.com/cachix/cachix-action/releases)
- [Commits](https://github.com/cachix/cachix-action/compare/ad2ddac53f961de1989924296a1f236fcfbaa4fc...0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad)

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

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

.github/workflows/codeowners-v2.yml

@@ -47,7 +47,7 @@ jobs:
     steps:
       - uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
 
-      - uses: cachix/cachix-action@ad2ddac53f961de1989924296a1f236fcfbaa4fc # v15
+      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           # This cache is for the nixpkgs repo checks and should not be trusted or used elsewhere.
           name: nixpkgs-ci

.github/workflows/manual-nixos-v2.yml

@@ -26,7 +26,7 @@ jobs:
         with:
           extra_nix_config: sandbox = true
 
-      - uses: cachix/cachix-action@ad2ddac53f961de1989924296a1f236fcfbaa4fc # v15
+      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         if: github.repository_owner == 'NixOS'
         with:
           # This cache is for the nixpkgs repo checks and should not be trusted or used elsewhere.

.github/workflows/manual-nixpkgs-v2.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           extra_nix_config: sandbox = true
 
-      - uses: cachix/cachix-action@ad2ddac53f961de1989924296a1f236fcfbaa4fc # v15
+      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         if: github.repository_owner == 'NixOS'
         with:
           # This cache is for the nixpkgs repo checks and should not be trusted or used elsewhere.