Update blinker to 1.6

[pyup-bot]

This PR updates blinker from 1.4 to 1.6.

Changelog

1.6

-----------

Released 2023-04-02

-   Add a muted context manager to temporarily turn off a
 signal. :pr:`84`
-   Allow int senders (alongside existing string senders). :pr:`83`
-   Add a send_async method to the Signal to allow signals to send to
 coroutine receivers. :pr:`76`
-   Update and modernise the project structure to match that used by the
 pallets projects. :pr:`77`
-   Add an intial set of type hints for the project.

1.5

-----------

Released 2022-07-17

-   Support Python >= 3.7 and PyPy. Python 2, Python < 3.7, and Jython
 may continue to work, but the next release will make incompatible
 changes.

Links

• PyPI: https://pypi.org/project/blinker
• Changelog: https://pyup.io/changelogs/blinker/

[pyup-bot]

Closing this in favor of #722