Add missing slots to _RequestContextManager and _WSRequestContextManager

[Pliner]

It seems that slots were forgotten in children of _BaseRequestContextManager

PR adds slots to _RequestContextManager and _WSRequestContextManager

Here is a very short sample to show the diff:

import sys


class ASlot:
    __slots__ = ("a", "b")

    def __init__(self):
        self.a = 42
        self.b = 24


class BNoSlot(ASlot):
    pass


class BSlot(ASlot):
    __slots__ = ()

print(sys.getsizeof(ASlot())) # 48
print(sys.getsizeof(BNoSlot())) # 64
print(sys.getsizeof(BSlot())) # 48

• 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]

Codecov Report

Merging #5329 (e3358c1) into master (cb4bae7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5329   +/-   ##
=======================================
  Coverage   97.16%   97.16%           
=======================================
  Files          41       41           
  Lines        8739     8739           
  Branches     1402     1402           
=======================================
  Hits         8491     8491           
  Misses        129      129           
  Partials      119      119           

Flag	Coverage Δ
unit	97.04% <ø> (ø)

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[asvetlov]

Thanks!

[aio-libs-github-bot]

💚 Backport successful

The PR was backported to the following branches:

• ✅ 3.8