github-actions/update: fix nix installation

.github/workflows/update.yml

@@ -6,6 +6,7 @@ on:
 
 jobs:
   lockfile:
+    name: Update the flake inputs and generate options
     runs-on: nscloud-ubuntu-22.04-amd64-4x16
     timeout-minutes: 40
     steps:
@@ -13,14 +14,20 @@ jobs:
         uses: actions/checkout@v3
         with:
           token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}
+
       - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@v1
+        uses: cachix/install-nix-action@v20
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Update flake.lock
         id: update
         uses: DeterminateSystems/update-flake-lock@v20
         with:
           pr-title: "Update flake.lock"
           token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}
+
       - name: Update autogenerated configs
         run: |
           git checkout update_flake_lock_action