chore(deps): update cachix/install-nix-action action to v31

Author: renovate[bot]

.github/workflows/prettier.yml

@@ -16,7 +16,7 @@ jobs:
               uses: actions/checkout@v4
 
             - name: Install the Nix package manager
-              uses: cachix/install-nix-action@v30
+              uses: cachix/install-nix-action@v31
 
             - name: Checks
               run: nix run nixpkgs#nodePackages.prettier -- --check .