bambootracker,bambootracker-qt6: Switch from vendored to system-installed RtAudio 6

pkgs/applications/audio/bambootracker/default.nix

···
 , qtbase
 , qttools
 , qtwayland
-, rtaudio
+, rtaudio_6
 , rtmidi
 , wrapQtAppsHook
 }:
···
 
   buildInputs = [
     qtbase
+    rtaudio_6
     rtmidi
   ] ++ lib.optionals stdenv.hostPlatform.isLinux [
     qtwayland
   ] ++ lib.optionals (lib.versionAtLeast qtbase.version "6.0") [
     qt5compat
-  ] ++ rtaudio.buildInputs;
+  ];
 
   qmakeFlags = [
-    # we don't have RtAudio 6 yet: https://github.com/NixOS/nixpkgs/pull/245075
-    # "CONFIG+=system_rtaudio"
+    "CONFIG+=system_rtaudio"
     "CONFIG+=system_rtmidi"
   ];