ci: update nix/cachix actions

Author: mrcjkb

.github/workflows/checks.yaml

@@ -9,9 +9,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - uses: cachix/install-nix-action@v24
-    # - uses: cachix/cachix-action@v12
-      # with:
-      #   name: neorocks
-      #   authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+    - uses: DeterminateSystems/nix-installer-action@main
+    - uses: DeterminateSystems/magic-nix-cache-action@main
     - run: nix flake check -L --accept-flake-config --option sandbox false

flake.nix

@@ -1,5 +1,10 @@
 {
-  description = "devShell for Rust projects";
+  description = "Edit toml files while preserving whitespace and formatting from Lua";
+
+  nixConfig = {
+    extra-substituters = "https://neorocks.cachix.org";
+    extra-trusted-public-keys = "neorocks.cachix.org-1:WqMESxmVTOJX7qoBC54TwrMMoVI1xAM+7yFin8NRfwk=";
+  };
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";