Fix typing on evalsha keys_and_args argument

[icgood]

What do these changes do?

Resolve the restrictive typing on evalsha keys_and_args argument.

Are there changes in behavior for the user?

No, this change only affects typing hints.

Related issue number

Fix #1214

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• Add a new news fragment into the CHANGES/ folder
  • name it <issue_id>.<type> (e.g. 588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the PR
  • ensure type is one of the following:
    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
    • .removal: Signifying a deprecation or removal of public API.
    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example:
    Fix issue with non-ascii contents in doctest text files.

[codecov]

Codecov Report

Merging #1215 (93278c1) into master (33b2dbd) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1215   +/-   ##
=======================================
  Coverage   89.21%   89.21%           
=======================================
  Files          21       21           
  Lines        6872     6872           
  Branches      794      794           
=======================================
  Hits         6131     6131           
  Misses        578      578           
  Partials      163      163           

Flag	Coverage Δ
unit	89.12% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
aioredis/client.py	82.55% <100.00%> (ø)

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[Andrew-Chen-Wang]

Thanks!