Update Rust crate tokio to v1.21.0

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
tokio (source)	dev-dependencies	minor	=1.20.1 -> =1.21.0
tokio (source)	dependencies	minor	=1.20.1 -> =1.21.0

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Release Notes

tokio-rs/tokio

v1.21.0

Compare Source

1.21.0 (September 2, 2022)

This release is the first release of Tokio to intentionally support WASM. The sync,macros,io-util,rt,time features are stabilized on WASM. Additionally the wasm32-wasi target is given unstable support for the net feature.

Added

• net: add device and bind_device methods to TCP/UDP sockets (#​4882)
• net: add tos and set_tos methods to TCP and UDP sockets (#​4877)
• net: add security flags to named pipe ServerOptions (#​4845)
• signal: add more windows signal handlers (#​4924)
• sync: add mpsc::Sender::max_capacity method (#​4904)
• sync: implement Weak version of mpsc::Sender (#​4595)
• task: add LocalSet::enter (#​4765)
• task: stabilize JoinSet and AbortHandle (#​4920)
• tokio: add track_caller to public APIs (#​4805, #​4848, #​4852)
• wasm: initial support for wasm32-wasi target (#​4716)

Fixed

• miri: improve miri compatibility by avoiding temporary references in linked_list::Link impls (#​4841)
• signal: don't register write interest on signal pipe (#​4898)
• sync: add #[must_use] to lock guards (#​4886)
• sync: fix hang when calling recv on closed and reopened broadcast channel (#​4867)
• task: propagate attributes on task-locals (#​4837)

Changed

• fs: change panic to error in File::start_seek (#​4897)
• io: reduce syscalls in poll_read (#​4840)
• process: use blocking threadpool for child stdio I/O (#​4824)
• signal: make SignalKind methods const (#​4956)

Internal changes

• rt: extract basic_scheduler::Config (#​4935)
• rt: move I/O driver into runtime module (#​4942)
• rt: rename internal scheduler types (#​4945)

Documented

• chore: fix typos and grammar (#​4858, #​4894, #​4928)
• io: fix typo in AsyncSeekExt::rewind docs (#​4893)
• net: add documentation to try_read() for zero-length buffers (#​4937)
• runtime: remove incorrect panic section for Builder::worker_threads (#​4849)
• sync: doc of watch::Sender::send improved (#​4959)
• task: add cancel safety docs to JoinHandle (#​4901)
• task: expand on cancellation of spawn_blocking (#​4811)
• time: clarify that the first tick of Interval::tick happens immediately (#​4951)

Unstable

• rt: add unstable option to disable the LIFO slot (#​4936)
• task: fix incorrect signature in Builder::spawn_on (#​4953)
• task: make task::Builder::spawn* methods fallible (#​4823)

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