ci: use nix-fast-build to build checks

.forgejo/workflows/check.yml

@@ -27,11 +27,4 @@ jobs:
               build --out-link /var/lib/gitea-runner/tankstelle/.local/state/nix/results/"$target" ".#nixosConfigurations.${target}.config.system.build.toplevel"
           done
 
-          for check in $(nix flake show --json --all-systems | jq --raw-output '
-            .checks."x86_64-linux" |
-            to_entries[] |
-            .key'
-          ); do
-            nix --print-build-logs --verbose --accept-flake-config --access-tokens '' \
-              build --out-link /var/lib/gitea-runner/tankstelle/.local/state/nix/results/"$check" ".#checks.x86_64-linux.${check}"
-          done
+          nix-fast-build --no-nom --systems "aarch64-linux x86_64-linux"

flake.nix

@@ -99,7 +99,7 @@
           devShells.default = pkgs.mkShell {
             buildInputs = with pkgs; [
               deploy-rs
-              nixpkgs-fmt
+              nix-fast-build
               agenix
               age-plugin-yubikey
               cachix