Remove allow(visible_private_types)
Remove allow(visible_private_types)

It's not needed and no longer supported by rustc anyway.

vosen/toml_document,alexcrichton/toml-rs,trlim/toml-rs,badboy/toml-rs,mseri/toml-rs,GuillaumeGomez/toml-rs,roguePanda/toml-rs,vosen/toml-rs