Uvloop

This release adds Python 3.10 support, updates bundled libuv to 1.42.0
and fixes a handful of issues.

Changes
=======

* Python 3.10 support (432)
(by elprans in 2519e2df for 432)

* Bump vendored libuv to 1.42.0 (433)
(by elprans in a62f7818 for 433)

* Use cibuildwheel to build wheels (435)
(by elprans in 20febe0b for 435)

* Add support for `<timer handle>.when()`
(by Jens Jorgensen in 62b2af9c)

Fixes
=====

* Fix ref issue when protocol is in Cython
(by fantix in 70cafc82 for 2222)

* Set `python_requires` in setup.py
(by graingert in c808a663)

* SSL: schedule first data after waiter wakeup
(by fantix in 2081db89)

* Fix a possible race condition in sslproto test
(by fantix in b0526cd5 for 412)

* Fix `call_soon_threadsafe` thread safety
(by fantix in 4b803b15)

Bug Fixes

* SSL: schedule first data after waiter wakeup
(by fantix in 0df12282)

* Fix a possible race condition in sslproto test
(by fantix in 2e71c4c2 for 412)

* Fix `call_soon_threadsafe` thread safety
(by fantix and hehaha in 6387a4e4 for 408)

Bug Fixes

* Add `python_requires` in `setup.py` to fix dependency resolution issues
(by graingert in c808a663)

Bug Fixes

* Fix a segfault issue when a Cython protocol is de-referencing itself from `Context.run()` callbacks
(by fantix in 70cafc82)

New Features

* Add name keyword argument to `loop.create_task()`
(by fantix in d51ce367 for 309)

* Add typing support
(by bryanforbes in 9426e2b1, for 358)

Bug Fixes

* SSL: many improvements
(by fantix in 6476aad6, 8beacd26, 98e113ee, ae44ec2d, asvetlov in 9bc4a204)

* Fix `KeyboardInterrupt` handling logic
(by 1st1 in c32c7039 for 295, jack1142 in 8c471f82 for 337)

* Python 3.8/3.9 compatibility fixes, drop support for 3.5/3.6
(by jack1142 in 28702195 for 314, achimnol in 0d14ec64 for 328, aeros in 6ef69a79 for 349, shadchin in 1fd90665, fantix in 465717fd, 200e1404, afc3ee8f, cdd2218f, b7048b94)

* UDP: multiple bug fixes
(by fantix in 1d9267af for 319, 9e017e6e for 304, 506a2aa1)

* Pipe: a critical crash fix that affects subprocess, pipe and socketpair
(by fantix in 5d41af80 and tardyp in c3929720 for 311 312 317)

* Restore context on protocol callbacks
(by versusvoid in 7b202ccf for 305, fantix in f691212b)

* Subprocess: stdio bug fixes
(by fantix in 8cdb3002 for 136, lovasoa in 68db1a23 for 363)

* Sock: fix issue in `sock_connect()` for large concurrency
(by fantix in fe3d0281 for 378)

* Misc fixes about docs URL, test typo, and CI compatibility
(by asfaltboy in 38105305, felixonmars in fcb37350, fantix in 6596685a)

Build

* Check Cython version semantically
(by YoSTEALTH in 5dc299b7)

* Add `.flake8` to distribution tarball
(by jlaine in e8eb5026 for 330)

* Switch to Github actions
(by elprans in 3be8967e, e21ceea0, fantix in 311997ed)

* Bump libuv to v1.40.0
(by fantix in 998c19ec)

New Features

* Add support for Python 3.8.
(by 1st1 in 5f48dab8, 51636f7b)

Bug Fixes

* Multiple fixes in the SSL/TLS layer.
(by fantix in 82104fb6 for 263, 7fcbfed1 for 255, e6fd6377)

* Restore `signal.wakeup_fd` after the event loop is closed.
(by vladima in 48d376d3, 1st1 in d76d9827)

* Handle large timeouts in `loop.call_later()`.
(by 1st1 in 1a0d6578 for 259)

* Fix possible feezing of uvloop on `os.fork`.
(by grungy-ado in fde5d14f)

* Better handle Unix sockets for datagram transports.
(by mosquito and 1st1 in dd4cb7ac for 269)

* Avoid double connecting to `remote_addr` for datagram transports.
(by 1st1 in bed926c5 for 276)

Build

* Bump Cython to 0.29.13.
(by 1st1 in 65c1a045)

* Bump libuv to v1.33.1.
(by 1st1 in 34fd827e)