Update cachix/install-nix-action digest to c134e4c

Author: renovate[bot]

.github/workflows/nix.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       # Install Nix on the runner
-      - uses: cachix/install-nix-action@f0fe604f8a612776892427721526b4c7cfb23aba # v31
+      - uses: cachix/install-nix-action@c134e4c9e34bac6cab09cf239815f9339aaaf84e # v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable
       # Pull from the cachix cache