Aio-pika

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* Fix badges in docs

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* Fix readthedocs build file

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The bulk of the changes are related to how the library entities are now
interconnected. In previous versions of `aio_pika.Channel` instances not
contains a link to the `aio_pika.Connection` instances for now is contains it.

While I don't want custom code to work directly with the `aiormq.Channel`
instance, this was a public API and I should warn you about the change here.
The `aio_pika.Channel.channel` property is deprecated. Use
`aio_pika.Channel.get_underlay_chanel()` instead.
Now all library entities already use this method.

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* Update aiormq version

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* Amend Exchange.__repr__ to include class name 527
Also switch to f-strings rather than %-formatting, modelled after
Queue.__repr__.
* Update example code of rpc tutorial 530
* bugfix: kwargs not working in `aio_pika.connect_robust` 531
* Improve type hints for `queue.get()` 542

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* Prevent 'Task exception was never retrieved' 524
If future.exception() is not called (even on cancelled futures), it seems Python
will then log 'Task exception was never retrieved'. Rewriting this logic
slightly should hopefully achieve the same functionality while
preventing the Python errors.
* Avoid implicitly depending on setuptools 526