Motivation for this change

Fix configure time error:

...
ImportError: No module named wx
CMake Error at CMakeModules/FindwxPython.cmake:52 (message):
  wxPython/Phoenix does not appear to be installed on the system

Only build tested. (I mean, the kicad program starts, but I don't know if the python scripting part works.)

Fixes: f7e28bf ("Split buildPythonPackage into setup hooks")

cc @FRidh for python changes.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @berce