Cherry pick sharded pubsub commit into 4.4

[noah-chae]

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Description of change

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[codecov-commenter]

Codecov Report

Patch coverage: 27.13% and project coverage change: -0.45% ⚠️

Comparison is base (e85e3f7) 60.59% compared to head (240ee07) 60.14%.

Additional details and impacted files

@@            Coverage Diff             @@
##              4.4      #10      +/-   ##
==========================================
- Coverage   60.59%   60.14%   -0.45%     
==========================================
  Files         116      116              
  Lines       29922    30242     +320     
==========================================
+ Hits        18130    18189      +59     
- Misses      11792    12053     +261     

Files Changed	Coverage Δ
tests/test_asyncio/test_pubsub.py	20.99% <ø> (ø)
redis/cluster.py	85.27% <15.71%> (-5.59%)	⬇️
tests/test_pubsub.py	57.22% <27.52%> (-15.60%)	⬇️
redis/client.py	67.87% <37.20%> (-1.76%)	⬇️
redis/commands/core.py	78.12% <50.00%> (-0.10%)	⬇️
redis/commands/parser.py	63.33% <100.00%> (ø)

... and 3 files with indirect coverage changes

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[zach-iee]

@noah-chae i think most of the codes are from existing redis-py master branch except for the push_handler_func. Am i correct?

[noah-chae]

@zach-iee That's right. It's just a cherry-pick & resolve merge conflict commit. But I don't know about push_handler_func 😲