Update cachix/install-nix-action action to v17

Author: renovate-bot

.github/workflows/ci-docs.yml

@@ -16,7 +16,7 @@ jobs:
       - uses: jorelali/setup-elm@v3
         with:
           elm-version: 0.19.1
-      - uses: cachix/install-nix-action@v16
+      - uses: cachix/install-nix-action@v17
         with:
           nix_path: nixpkgs=channel:nixos-21.11
       - name: Print nixpkgs version

.github/workflows/website.yml

@@ -15,7 +15,7 @@ jobs:
       - uses: jorelali/setup-elm@v3
         with:
           elm-version: 0.19.1
-      - uses: cachix/install-nix-action@v16
+      - uses: cachix/install-nix-action@v17
         with:
           nix_path: nixpkgs=channel:nixos-21.11
       - name: Print nixpkgs version