fix: pkgs.system is now pkgs.stdenv.hostPlatform.system

Caused by NixOS/nixpkgs#456527

Fixes #137 and #119

Author: zimbatm

lib/default.nix

@@ -683,13 +683,13 @@ let
             # add nixos system closures to checks
             (withPrefix "nixos-" (
               lib.mapAttrs (_: x: x.config.system.build.toplevel) (
-                lib.filterAttrs (_: x: x.pkgs.system == system) (inputs.self.nixosConfigurations or { })
+                lib.filterAttrs (_: x: x.pkgs.stdenv.hostPlatform.system == system) (inputs.self.nixosConfigurations or { })
               )
             ))
             # add darwin system closures to checks
             (withPrefix "darwin-" (
               lib.mapAttrs (_: x: x.system) (
-                lib.filterAttrs (_: x: x.pkgs.system == system) (inputs.self.darwinConfigurations or { })
+                lib.filterAttrs (_: x: x.pkgs.stdenv.hostPlatform.system == system) (inputs.self.darwinConfigurations or { })
               )
             ))
             # add system-manager closures to checks

templates/toml-devenvs/checks/bye-devshell.nix

@@ -1,7 +1,7 @@
 { pkgs, inputs, ... }:
 let
   # defined in devshells/bye.nix
-  shell = inputs.self.devShells.${pkgs.system}.bye;
+  shell = inputs.self.devShells.${pkgs.stdenv.hostPlatform.system}.bye;
 in
 pkgs.stdenvNoCC.mkDerivation {
   name = "hello-devshell";

templates/toml-devenvs/checks/default-devshell.nix

@@ -1,7 +1,7 @@
 { pkgs, inputs, ... }:
 let
   # defined in devshell.toml at root of this flake.
-  shell = inputs.self.devShells.${pkgs.system}.default;
+  shell = inputs.self.devShells.${pkgs.stdenv.hostPlatform.system}.default;
 in
 pkgs.stdenvNoCC.mkDerivation {
   name = "default-devshell";