sonic-pi: add ruby to nativeBuildInputs

The ruby interpreter is used during the configure and build phases in
addition to the check phase, so add it to nativeBuildInputs instead of
checkInputs.

pkgs/applications/audio/sonic-pi/default.nix

@@ -63,6 +63,7 @@ stdenv.mkDerivation rec {
     copyDesktopItems
     cmake
     pkg-config
+    ruby
     erlang
     elixir
     beamPackages.hex
@@ -94,7 +95,6 @@ stdenv.mkDerivation rec {
 
   checkInputs = [
     parallel
-    ruby
     supercollider-with-sc3-plugins
     jack2
   ];