Update ALL install-nix-actions

Author: pietdevries94

.github/workflows/auto-update.yml

@@ -10,7 +10,7 @@ jobs:
       updated: ${{ steps.updated.outputs.updated }}
     steps:
       - uses: actions/checkout@v4
-      - uses: cachix/install-nix-action@v27
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
@@ -38,7 +38,7 @@ jobs:
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: cachix/install-nix-action@v27
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
@@ -62,7 +62,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
-      - uses: cachix/install-nix-action@v27
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable
       - run: ./update.sh