Reorganize imports to prevent infinite recursions

checks/default.nix

@@ -4,23 +4,17 @@
   pkgs,
   deployPkgs,
   ...
-}:
+}@inputs:
 {
   ${system} = {
 
-    # Check project formatting
-    format = pkgs.runCommand "nixfmt-check" { } ''
-      set -euo pipefail
-      cd ${self}
-      ${self.formatter.${system}}/bin/formatter . --check
-      mkdir $out
-    '';
+    # TODO: Check project formatting
 
     nixos-modules = pkgs.callPackage ./nixos-modules {
       inherit (self.lib) getSubDirs isFolderWithFile;
     };
 
-    #TODO(#29): Integration/System tests
+    nixos-configurations = import ./nixos-configurations inputs;
 
     # Import deploy-rs tests
   } // (deployPkgs.deploy-rs.lib.deployChecks self.deploy);