MNT add funding file to apply to floss.fund

[adrinjalali]

This is to apply for https://floss.fund/ which requires this file somewhere. I'd remove the file once the decision on the funding is made, either accept or reject.

Would this be okay @BenjaminBossan

[BenjaminBossan]

I haven't heard of this fund, but 🤞 that it works out.

Also feel free to remove me from the maintainers list if it helps, since, realistically, I'm not doing maintenance work on skops anymore.

[adrinjalali]

I still appreciate your reviews and it's nice not to have a single person with permissions, at least until we find a new maintainer.