Triple quote docstrings in client.py PEP 257

[Andrew-Chen-Wang]

Pull Request check-list

Please make sure to review and check all of these items:

• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?

NOTE: these things are not required to open a PR and can be done
afterwards / while the PR is open.

Description of change

Please provide a description of the change here.

[codecov-commenter]

Codecov Report

Merging #1876 (56314fc) into master (41cef47) will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1876      +/-   ##
==========================================
+ Coverage   93.60%   93.63%   +0.02%     
==========================================
  Files          76       76              
  Lines       16268    16268              
==========================================
+ Hits        15228    15232       +4     
+ Misses       1040     1036       -4     

Impacted Files	Coverage Δ
redis/client.py	89.37% <ø> (ø)
tests/test_cluster.py	98.41% <0.00%> (+0.25%)	⬆️

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[chayim]

Thanks @Andrew-Chen-Wang . Fantastic! These things really improve the project.

This got me thinking, I found a flake8 plugin that I think could be helpful here.