trio 0.31.0 on Python PyPI

Full Changelog: v0.30.0...v0.31.0

Features

Cancelled strings can now display the source and reason for a cancellation. Trio-internal sources of cancellation will set this string, and CancelScope.cancel now has a reason string parameter that can be used to attach info to any Cancelled to help in debugging. (#3232)

Make ctrl+c work in more situations in the Trio REPL (python -m trio). (#3007)
Allow pickling trio.Cancelled, as they can show up when you want to pickle something else. This does not rule out pickling other NoPublicConstructor objects -- create an issue if necessary. (#3248)
Decrease import time on Windows by around 10%. (#3263)
Handle unwrapping SystemExit/KeyboardInterrupt exception gracefully in utility function raise_single_exception_from_group that reraises last exception from group. (#3275)
Ensure that the DTLS server does not mutate SSL context. (#3277)
Avoid having trio.as_safe_channel raise if closing the generator wrapped
GeneratorExit in a BaseExceptionGroup. (#3324)

Implement bool(trio.Event) and have it raise a DeprecationWarning and tell users to use trio.Event.is_set instead. This is an alternative to mypy --enable-error-code=truthy-bool for users who don't use type checking. (#3322)

When misnesting nurseries you now get a helpful RuntimeError instead of a catastrophic TrioInternalError. (#3307)