chore(deps): update redis

[jguillon]

Description

A security issue affected redis-py package. As users, we would like to be able to use dramatiq-abort with more recent version of redis-py (>=4.3.6).

Fixes #19

Checklist

• I have performed tests using the tox command.

[isra17]

Seems like a new version of the linter is unhappy with our code:

  ./src/dramatiq_abort/backends/__init__.py:8:5: B028 No explicit stacklevel keyword argument found. The warn method from the warnings module uses a stacklevel of 1 by default. This will only show a stack trace for the line on which the warn method is called. It is therefore recommended to use a stacklevel of 2 or greater to provide more information to the user.

Would you mind adding a stacklevel=2 to the warning call?