fix(deps): update rust crate ipc-channel to 0.21

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
ipc-channel	dependencies	minor	0.20 → 0.21

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Release Notes

servo/ipc-channel (ipc-channel)

v0.21.0

Compare Source

Highlights

(de)serialization error types are now opaque which allows us to switch (de)serialization library without breaking API. This release also switched from bincode to postcard for (de)serialization.

What's Changed

• Switch to serde_core by @​Narfinger in #​419
• Support one-shot router handlers by @​jdm in #​418
• Cleaned up memory dance in ipc::send and ipc::to. by @​Narfinger in #​421
• Remove PartialEq from OsIpcSender and OsIpcReceiver by @​jschwe in #​416
• Notice callback drop timing in add_route by @​Legend-Master in #​431
• Switch from fnv to rustc_hash by @​Narfinger in #​430
• Unify error handling to have IpcError and TryRecvError be the main errortypes. by @​Narfinger in #​407
• Switch to Postcard by @​Narfinger in #​432
• Disconnect non-empty channel docs by @​glyn in #​437
• Non-blocking variants of IpcReceiverSet::select by @​glyn in #​435
• Re-export SerDeError since it should be part of the API by @​glyn in #​438
• Allow IpcSharedMemory to support a take function that might be more efficient by @​Narfinger in #​433
• Postcard remove default embedded dependencies by @​Narfinger in #​440

New Contributors

• @​ChristianBelloni made their first contribution in #​426
• @​Legend-Master made their first contribution in #​431

Full Changelog: servo/ipc-channel@v0.20.2...v0.21.0

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