Drop deprecated timeouts in ClientSession constructor

[atemate]

What do these changes do?

Drop deprecated arguments read_timeout and conn_timeout in ClientSession constructor.

Are there changes in behavior for the user?

no more arguments read_timeout and conn_timeout in ClientSession constructor.

Related issue number

closes #3890

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> for example (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-io]

Codecov Report

Merging #3891 into master will decrease coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #3891     +/-   ##
=========================================
- Coverage   97.81%   97.72%   -0.1%     
=========================================
  Files          43       43             
  Lines        8666     8666             
  Branches     1386     1386             
=========================================
- Hits         8477     8469      -8     
- Misses         82       89      +7     
- Partials      107      108      +1

Impacted Files	Coverage Δ
aiohttp/locks.py	92.85% <0%> (-7.15%)	⬇️
aiohttp/web_fileresponse.py	96.55% <0%> (-1.15%)	⬇️
aiohttp/streams.py	97.92% <0%> (-0.52%)	⬇️
aiohttp/helpers.py	96.95% <0%> (-0.51%)	⬇️

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