ci: nix: add binary cache

Author: RCasatta

.github/workflows/rust.yml

@@ -51,5 +51,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: cachix/install-nix-action@v25
+        with:
+          extra_nix_config: |
+            trusted-public-keys = nix.casatta.it:HseKZh7436/vKXfZDBHbhr7wwAkzjLwY5BIq+OOrITg= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+            substituters = https://nix.casatta.it https://cache.nixos.org/
       - run: nix build .