Fonts are not build when assets is call

[BellemareMederic]

Description

Hello there, i just found your plugins to export grav to static HTML.

And i just realize that fonts are not compile in the build folder when we call the generate function
bin/plugin blackhole generate http://127.0.0.1:8000/ --assets --output-path ./build

Reproduce

1. Install the default version of Grav theme with the default page
2. execute the generate command
3. visit the build folder \build\user\themes\quark\fonts is missing

thinking

I think all fonts is an assets to ? or im wrong ^_^ im not sure

thanks for all your work body 🙌

[jlounds]

I have run into a similar problem where images referenced in the CSS are not copied as an asset. It would be great if this could work, but the workaround I have for now is to copy all of the theme assets manually.