Fix stale VoxelGI warnings.

Easy 1 line fix, just need to call update_configuration_warnings()
any time fields related to our warning concerns get changed. In
this case it's we just need to be concerned about calling this
whenever the voxel data field changes for any reason.

scene/3d/voxel_gi.cpp

@@ -275,6 +275,7 @@ void VoxelGI::set_probe_data(const Ref<VoxelGIData> &p_data) {
 	}
 
 	probe_data = p_data;
+	update_configuration_warnings();
 }
 
 Ref<VoxelGIData> VoxelGI::get_probe_data() const {