Do not assume Python 3.14 has stdlib zstd

[JacobHenner]

Do not assume Python 3.14 has compression.zstd available, as that module depends on a shared library version that is not available on all platforms and distributions (e.g. Rocky Linux 8).

What do these changes do?

Prevents errors when using aiohttp from a Python 3.14 build that does not include compression.zstd support.

Are there changes in behavior for the user?

Fixes bug.

Is it a substantial burden for the maintainers to support this?

No

Related issue number

Fixes #11603

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_or_pr_num>.<type>.rst (e.g. 588.bugfix.rst)

  • if you don't have an issue number, change it to the pull request
    number after creating the PR

    • .bugfix: A bug fix for something the maintainers deemed an
      improper undesired behavior that got corrected to match
      pre-agreed expectations.
    • .feature: A new behavior, public APIs. That sort of stuff.
    • .deprecation: A declaration of future API removals and breaking
      changes in behavior.
    • .breaking: When something public is removed in a breaking way.
      Could be deprecated in an earlier release.
    • .doc: Notable updates to the documentation structure or build
      process.
    • .packaging: Notes for downstreams about unobvious side effects
      and tooling. Changes in the test invocation considerations and
      runtime assumptions.
    • .contrib: Stuff that affects the contributor experience. e.g.
      Running tests, building the docs, setting up the development
      environment.
    • .misc: Changes that are hard to assign to any of the above
      categories.

  • Make sure to use full sentences with correct case and punctuation,
    for example:

    Fixed issue with non-ascii contents in doctest text files
    -- by :user:`contributor-gh-handle`.

    Use the past tense or the present tense a non-imperative mood,
    referring to what's changed compared to the last released version
    of this project.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.74%. Comparing base (80eb0aa) to head (2878f32).
⚠️ Report is 3233 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11611      +/-   ##
==========================================
+ Coverage   98.19%   98.74%   +0.55%     
==========================================
  Files         128      127       -1     
  Lines       43758    43450     -308     
  Branches     2386     2325      -61     
==========================================
- Hits        42967    42905      -62     
+ Misses        610      389     -221     
+ Partials      181      156      -25     

Flag	Coverage Δ
CI-GHA	98.63% <100.00%> (+0.55%)	⬆️
OS-Linux	98.36% <100.00%> (+0.53%)	⬆️
OS-Windows	96.69% <100.00%> (+1.15%)	⬆️
OS-macOS	97.58% <100.00%> (+0.51%)	⬆️
Py-3.10.11	97.15% <100.00%> (+0.56%)	⬆️
Py-3.10.18	97.65% <100.00%> (+0.56%)	⬆️
Py-3.11.13	97.84% <100.00%> (+0.50%)	⬆️
Py-3.11.9	97.35% <100.00%> (+0.51%)	⬆️
Py-3.12.10	97.45% <100.00%> (+0.52%)	⬆️
Py-3.12.11	97.95% <100.00%> (+0.51%)	⬆️
Py-3.13.7	98.21% <100.00%> (+0.54%)	⬆️
Py-3.14.0	98.15% <66.66%> (?)
Py-3.14.0-rc.3	?
Py-3.14.0-rc.3t	?
Py-3.14.0t	97.22% <66.66%> (?)
Py-pypy3.10.16-7.3.19	87.97% <66.66%> (+0.16%)	⬆️
VM-macos	97.58% <100.00%> (+0.51%)	⬆️
VM-ubuntu	98.36% <100.00%> (+0.53%)	⬆️
VM-windows	96.69% <100.00%> (+1.15%)	⬆️

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[codspeed]

CodSpeed Performance Report

Merging #11611 will not alter performance

_{Comparing JacobHenner:fix/do-not-assume-stdlib-zstd (2878f32) with master (35754d4)¹}

Summary

✅ 59 untouched

Footnotes

1. No successful run was found on master (9f718eb) during the generation of this report, so 35754d4 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[patchback]

Backport to 3.13: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.13/49290944c0d098a85dd867a9e331cfb33a802199/pr-11611

Backported as #11612

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.14: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.14/49290944c0d098a85dd867a9e331cfb33a802199/pr-11611

Backported as #11613

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.