Gtk-Message: 23:48:13.069: Failed to load module "canberra-gtk-module"

Hi,

on the [Gtk-site](https://juliagraphics.github.io/Gtk.jl/latest/#) I found the advice:

> On some platforms, you may see messages like
> Gtk-Message: 20:15:48.288: Failed to load module "canberra-gtk-module"
> These are harmless. If you want to suppress them, on Unix platforms you can add something like
> export GTK_PATH=$GTK_PATH:/usr/lib/x86_64-linux-gnu/gtk-3.0
>

But this does not solve the issue under `kubuntu`.

If I run the following minimal example:
```
using PlotlyJS
PlotlyJS.Plot([1,2,3])
```
in a julia session inside a terminal window the error message is:

```
julia> Gtk-Message: 00:02:42.519: Failed to load module "canberra-gtk-module"
Gtk-Message: 00:02:42.521: Failed to load module "canberra-gtk-module"
```

And I have ( - of course - ) installed the related package:
```
sudo apt install libcanberra-gtk-module
```
Any ideas?