message: mention to GATs isn't really necessary
diff: //! Utilities for pagination requests. If the configured client is asynchronous,
  //! it'll be based on `futures::stream::Stream`, if it's synchronous it'll just
  //! use `std::iter::Iterator`.
  -//!
  -//! In the future, this may be extended to use the same interface for all
  -//! manual, synchronous and asynchronous iteration with a nicer interface. The
  -//! problem is that it requires GATs to be implemented. See this comment:
  -//! `<https://github.com/ramsayleung/rspotify/pull/166#issuecomment-793698024>`
  #[cfg(feature = "__sync")]
  mod iter;
  