Undo enabling the `unreachable-pub` lint.
It appears that nom cannot correctly handle `pub(crate)`,
so the warnings cannot be fixed at the moment.
See https://github.com/Geal/nom/issues/807
neglected dep update from
r87a6cad20c90:
that rev also forces nightly rust due to https://github.com/rust-lang/rust/issues/23121