Update aio_pika to 6.8.0

[pyup-bot]

This PR updates aio_pika from 6.3.0 to 6.8.0.

Changelog

6.8.0

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* fix: master deserialize types 366
* fix: add missing type hint on exchange publish method 370
* Return self instead of select result in `__aenter__` 373
* fix: call remove_close_callback 374

6.7.1

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* Fix breaking change in callback definition 344

6.7.0

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* Reworked tests and finally applied PR 311
* Improve documentation examples and snippets 339
* Restore RobustChannel.default_exchange on reconnect 340
* Improve the docs a bit 335

6.6.1

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* Add generics to Pool and PoolItemContextManager 321
* Fix Docs for ``DeliveryError`` 322

6.6.0

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* message.reject called inside ProcessContext.__exit__ fails when channel is closed 302

6.5.3

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* Add docs and github links to setup.py 304

6.5.2

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* Type annotation fixes
* Add documentation

6.5.1

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* Test fixes
* Add reopen method for channel 263

6.5.0

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* Add get methods for exchange and queue 282
* fix type annotation and documentation for Connection.add_close_callback 290

6.4.3

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* log channel close status
* add OSError to `CONNECTION_EXCEPTIONS`

6.4.2

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* [fix] heartbeat_last to heartbeat_last_received 274
* Fix memory leak 285
* Fix type hint 287
* Pass loop when connecting to aiormq 294

6.4.1

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* RobustConnection cleanup fixes 273

6.4.0

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* aiormq updates:
 * Fixes for python 3.8
 [69](https://github.com/mosquito/aiormq/pull/69)
 [67](https://github.com/mosquito/aiormq/pull/67)
 * [passing ``name=`` query parameter](https://github.com/mosquito/aiormq/pull/69/commits/a967502e6dbdf5de422cfb183932bcec134250ad)
 from URL to user defined connection name (Rabbitmq 3.8+)
 * Fix connection drain [68](https://github.com/mosquito/aiormq/pull/68)
 * Remove ``loop=`` argument from asyncio entities [67](https://github.com/mosquito/aiormq/pull/67)
 * ChannelInvalidStateError exceptions instead of RuntimeError
 [65](https://github.com/mosquito/aiormq/pull/65)
* Update tests for python 3.8
* ``Pool.close()`` method and allow to use ``Pool`` as a context manager
[269](https://github.com/mosquito/aio-pika/pull/269)
* Fix stuck of ``RobustConnection`` when exclusive queues still locked
on server-side [267](https://github.com/mosquito/aio-pika/pull/267)
* Add ``global_`` parameter to ``Channel.set_qos`` method
[266](https://github.com/mosquito/aio-pika/pull/266)
* Fix ``Connection.drain()`` is ``None``
[Fix connection drain](https://github.com/mosquito/aiormq/pull/68)

Links

• PyPI: https://pypi.org/project/aio-pika
• Changelog: https://pyup.io/changelogs/aio-pika/