LADSPA: Update version to 1.15
The 1.13 tarball has been dropped from the project Website, note that the 1.13 tarball has been backed up on GStreamer mirror so that the fallback can work for cerbero builds without this update.
cc @a-morales
The 1.13 tarball has been dropped from the project Website, note that the 1.13 tarball has been backed up on GStreamer mirror so that the fallback can work for cerbero builds without this update.
cc @a-morales