Will panic on newer rust due to outdated `tokio` dependency

[5225225]

Hello!

I'm coming to this repo from rust-lang/rust#99389 where we're making the checks for uninitialized data stricter. This crate runs into them. Here's a backtrace, it looks like the tokio dep needs upgrading?

---- protocol::test::test_invalid_async stdout ----
thread 'protocol::test::test_invalid_async' panicked at 'attempted to leave type `[tokio_sync::loom::sync::CausalCell<core::mem::manually_drop::ManuallyDrop<core::result::Result<protocol::Message, error::Error>>>; 32]` uninitialized, which is invalid', /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/block.rs:366:24
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: core::mem::uninitialized
             at /home/jess/src/rust/library/core/src/mem/mod.rs:685:9
   4: tokio_sync::mpsc::block::Values<T>::uninitialized
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/block.rs:366:24
   5: tokio_sync::mpsc::block::Block<T>::new
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/block.rs:91:30
   6: tokio_sync::mpsc::list::channel
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/list.rs:38:34
   7: tokio_sync::mpsc::chan::channel
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/chan.rs:138:20
   8: tokio_sync::mpsc::bounded::channel
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/bounded.rs:118:20
   9: tt::protocol::test::test_invalid_async
             at ./src/protocol.rs:953:32
  10: tt::protocol::test::test_invalid_async::{{closure}}
             at ./src/protocol.rs:951:5
  11: core::ops::function::FnOnce::call_once
             at /home/jess/src/rust/library/core/src/ops/function.rs:248:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

---- protocol::test::test_read_write_async stdout ----
thread 'protocol::test::test_read_write_async' panicked at 'attempted to leave type `[tokio_sync::loom::sync::CausalCell<core::mem::manually_drop::ManuallyDrop<core::result::Result<protocol::Message, error::Error>>>; 32]` uninitialized, which is invalid', /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/block.rs:366:24
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: core::mem::uninitialized
             at /home/jess/src/rust/library/core/src/mem/mod.rs:685:9
   4: tokio_sync::mpsc::block::Values<T>::uninitialized
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/block.rs:366:24
   5: tokio_sync::mpsc::block::Block<T>::new
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/block.rs:91:30
   6: tokio_sync::mpsc::list::channel
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/list.rs:38:34
   7: tokio_sync::mpsc::chan::channel
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/chan.rs:138:20
   8: tokio_sync::mpsc::bounded::channel
             at /home/jess/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-sync-0.1.7/src/mpsc/bounded.rs:118:20
   9: tt::protocol::test::test_read_write_async
             at ./src/protocol.rs:916:32
  10: tt::protocol::test::test_read_write_async::{{closure}}
             at ./src/protocol.rs:914:5
  11: core::ops::function::FnOnce::call_once
             at /home/jess/src/rust/library/core/src/ops/function.rs:248:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.


failures:
    protocol::test::test_invalid_async
    protocol::test::test_read_write_async

It's unclear if this is only an issue in the tests, or if it will also run into the issues in usage.