Inkscape 1.1 compatible

[kuhnchris]

Making the plugins compatible with Inkscape 1.1.

Works for my example file:

[wawanbreton]

@jespino Please someone accept this pull request, I just spent 1 hour doing the same fix, until it realized someone already did it :)

[kuhnchris]

Not sure but it looks like @jespino seems either inactive nor not aware of the changes. Maybe I should just fork?

[wawanbreton]

That's why I mentioned him in the message, but that will probably be useless. You have already forked a repository, maybe you should have it referenced on https://inkscape.org/~Xaviju/%E2%98%85inkscape-export-layers-extension, that's how I got here.