nixosTests.power-profiles-daemon: add to all-tests.nix

This was forgotten in the inital PR.

nixos/tests/all-tests.nix

···
   postgresql = handleTest ./postgresql.nix {};
   postgresql-wal-receiver = handleTest ./postgresql-wal-receiver.nix {};
   powerdns = handleTest ./powerdns.nix {};
+  power-profiles-daemon = handleTest ./power-profiles-daemon.nix {};
   pppd = handleTest ./pppd.nix {};
   predictable-interface-names = handleTest ./predictable-interface-names.nix {};
   printing = handleTest ./printing.nix {};

pkgs/os-specific/linux/power-profiles-daemon/default.nix

···
 , systemd
 , python3
 , wrapGAppsNoGuiHook
+, nixosTests
 }:
 
 stdenv.mkDerivation rec {
···
     # Make Python libraries available
     wrapPythonProgramsIn "$out/bin" "$pythonPath"
   '';
+
+  passthru = {
+    tests = {
+      nixos = nixosTests.power-profiles-daemon;
+    };
+  };
 
   meta = with lib; {
     homepage = "https://gitlab.freedesktop.org/hadess/power-profiles-daemon";