Bump websockets from 8.1 to 9.0

[dependabot]

Bumps websockets from 8.1 to 9.0.

Changelog

Sourced from websockets's changelog.

9.0 ...

May 1, 2021

.. note::

**Version 9.0 moves or deprecates several APIs.**
Aliases provide backwards compatibility for all previously public APIs.


:class:~datastructures.Headers and
:exc:~datastructures.MultipleValuesError were moved from
websockets.http to :mod:websockets.datastructures. If you're using
them, you should adjust the import path.


The client, server, protocol, and auth modules were
moved from the websockets package to websockets.legacy
sub-package, as part of an upcoming refactoring. Despite the name,
they're still fully supported. The refactoring should be a transparent
upgrade for most uses when it's available. The legacy implementation
will be preserved according to the backwards-compatibility policy_.


The framing, handshake, headers, http, and uri
modules in the websockets package are deprecated. These modules
provided low-level APIs for reuse by other WebSocket implementations,
but that never happened. Keeping these APIs public makes it more
difficult to improve websockets for no actual benefit.

• Added compatibility with Python 3.9.

• Added support for IRIs in addition to URIs.

• Added close codes 1012, 1013, and 1014.

• Raised an error when passing a :class:dict to :meth:~legacy.protocol.WebSocketCommonProtocol.send.

• Fixed sending fragmented, compressed messages.

• Fixed Host header sent when connecting to an IPv6 address.

• Fixed creating a client or a server with an existing Unix socket.

• Aligned maximum cookie size with popular web browsers.

• Ensured cancellation always propagates, even on Python versions where :exc:~asyncio.CancelledError inherits :exc:Exception.

• Improved error reporting.

Commits

• 5ab214b Bump version number
• 9272873 Work around coverage bug.
• d82a7a9 Revamp API documentation.
• fcb3a4c Remove backwards-compatibility from docs after 5 years.
• 9223d7d Restore backwards-compatibility for logger names.
• 9c81836 Support existing Unix sockets in unix_connect.
• cf24536 Clean up signature of Protocol classes.
• 835d16d Add example of client shutdown.
• fa295a7 Rewrite extensions guide.
• c000260 Make HeadersLike a public API.
• Additional commits viewable in compare view

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[dependabot]

OK, I won't notify you again about this release, but will get in touch when a new version is available.

If you change your mind, just re-open this PR and I'll resolve any conflicts on it.

[dependabot]

Superseded by #3.