Make type hints for http parser stricter

[asvetlov]

A part of work on #5220

[codecov]

Codecov Report

Merging #5267 (13968f7) into master (bb53507) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5267      +/-   ##
==========================================
+ Coverage   97.52%   97.54%   +0.02%     
==========================================
  Files          43       43              
  Lines        8803     8806       +3     
  Branches     1415     1415              
==========================================
+ Hits         8585     8590       +5     
+ Misses        103      101       -2     
  Partials      115      115              

Flag	Coverage Δ
unit	97.37% <100.00%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
aiohttp/client_exceptions.py	98.33% <100.00%> (+0.01%)	⬆️
aiohttp/client_proto.py	96.66% <100.00%> (ø)
aiohttp/http_parser.py	97.14% <100.00%> (+0.45%)	⬆️
aiohttp/web_protocol.py	92.28% <100.00%> (ø)

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[aio-libs-github-bot]

💔 Backport was not successful

The PR was attempted backported to the following branches:

• ❌ 3.8: Commit could not be cherrypicked due to conflicts