Fix "systems deprecated" warning

overlays/default.nix

@@ -2,19 +2,19 @@
   # For every flake input, aliases 'pkgs.inputs.${flake}' to
   # 'inputs.${flake}.packages.${pkgs.system}' or
   # 'inputs.${flake}.legacyPackages.${pkgs.system}'
-  flake-inputs = final: _: {
+  # flake-inputs = final: _: {
-    inputs =
+  #   inputs =
-      builtins.mapAttrs (
+  #     builtins.mapAttrs (
-        _: flake: let
+  #       _: flake: let
-          legacyPackages = (flake.legacyPackages or {}).${final.system} or {};
+  #         legacyPackages = (flake.legacyPackages or {}).${final.system} or {};
-          packages = (flake.packages or {}).${final.system} or {};
+  #         packages = (flake.packages or {}).${final.system} or {};
-        in
+  #       in
-          if legacyPackages != {}
+  #         if legacyPackages != {}
-          then legacyPackages
+  #         then legacyPackages
-          else packages
+  #         else packages
-      )
+  #     )
-      inputs;
+  #     inputs;
-  };
+  # };
 
   input-flake-packages = final: prev: {
     sheet-organizer = inputs.sheet-organizer.packages.${prev.system}.default; # TODO: change sheet-organizer package output
@@ -26,11 +26,11 @@
 
   nixpkgs-stable-unstable = final: prev: {
     unstable = import inputs.nixpkgs-unstable {
-      system = prev.system;
+      system = prev.stdenv.hostPlatform.system;
       config.allowUnfree = true;
     };
     stable = import inputs.nixpkgs {
-      system = prev.system;
+      system = prev.stdenv.hostPlatform.system;
       config.allowUnfree = true;
     };
   };