Update websockets to 9.0.2

[pyup-bot]

This PR updates websockets from 8.1 to 9.0.2.

Changelog

9.0.2

.....

*May 15, 2021*

* Restored compatibility of ``python -m websockets`` with Python < 3.9.

* Restored compatibility with mypy.

9.0.1

.....

*May 2, 2021*

* Fixed issues with the packaging of the 9.0 release.

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.

.. note::

 **Version 9.0 may require changes if you use static code analysis tools.**

 Convenience imports from the ``websockets`` module are performed lazily.
 While this is supported by Python, static code analysis tools such as mypy
 are unable to understand the behavior.

 If you depend on such tools, use the real import path, which can be found
 in the API documentation::

     from websockets.client import connect
     from websockets.server import serve

* 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.

Links

• PyPI: https://pypi.org/project/websockets
• Changelog: https://pyup.io/changelogs/websockets/
• Repo: https://github.com/aaugustin/websockets

[pyup-bot]

Closing this in favor of #3044