Carla: add python3 to hostmakedepends

Let's see if that fixes py3_sitelib being unset.

Signed-off-by: Jürgen Buchmüller <pullmoll@t-online.de>

srcpkgs/Carla/template

@@ -5,7 +5,7 @@ revision=2
 build_style=gnu-makefile
 pycompile_module="carla_utils.py carla_backend.py"
 pycompile_dirs="usr/share/carla"
-hostmakedepends="pkg-config"
+hostmakedepends="pkg-config python3"
 makedepends="
  python3-PyQt5-devel-tools python3-PyQt5 libmagic file-devel liblo-devel
  alsa-lib-devel pulseaudio-devel libX11-devel gtk+3-devel gtk+-devel qt5-devel