Fixes the following warning is shown when installing/removing a language:
(io.elementary.switchboard:8612): GLib-GObject-WARNING **: 16:07:38.596: ../../../../gobject/gbinding.c:857: The source object of type SwitchboardPlugLocaleInstallerUbuntuInstaller has no property called 'install-cancellable'
Fixes the following warning is shown when installing/removing a language: