Motivation for this change

Optional dependency of orca

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-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 nox --run "nox-review wip"

• Tested execution of all binary files (usually in ./result/bin/)

  nix-shell -p liblouis --run "echo 'Quick brown fox' | lou_translate --forward en-us-g2.ctb"
  
  nix-shell -p liblouis python3 --pure --run "python -c \"import louis; print(louis.translate([b'en-us-g2.ctb'], 'Hello world!', cursorPos=5))\""
  

• Fits CONTRIBUTING.md.

cc @berce