PYTHON-6158 Clean up version-gated code paths

[aclark4life]

PYTHON-6158

Changes in this PR

Follow-up to PYTHON-6138 (drop Python 3.9 and 3.10). Removes version-gated code paths that are now dead on Python 3.11+:

• Delete pymongo/_asyncio_task.py, callers use asyncio.create_task.
• Import Self from typing unconditionally in pymongo/cursor_shared.py.
• Remove the Python 3.11 gate on async TLS session injection in pymongo/pool_shared.py.
• Use zip(..., strict=True) unconditionally in pymongo/pool_options.py.
• Remove the Python 3.9/3.10 anext/aiter fallbacks in pymongo/asynchronous/helpers.py.
• Remove dead 3.10/3.11 gates in tests.

Test Plan

Checklist

Checklist for Author

• Did you update the changelog (if necessary)?
• Is the intention of the code captured in relevant tests?
• If there are new TODOs, has a related JIRA ticket been created?

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Have you checked for spelling & grammar errors?
• Is all relevant documentation (README or docstring) updated?

[Copilot]

🟢 Approval recommended

The removed branches only support now-unsupported Python versions, and the replacements preserve existing Python 3.11+ behavior.

0 open findings

What changed in this PR

Removes obsolete compatibility paths after raising the minimum supported Python version to 3.11.

Changes:

• Replaces the custom task wrapper with asyncio.create_task.
• Removes dead version checks and compatibility fallbacks.
• Enables Python 3.11+ test paths unconditionally.

File	Description
pymongo/​_asyncio_task.py	Removes the obsolete task compatibility module.
pymongo/​asynchronous/​helpers.py	Uses built-in anext and aiter.
pymongo/​synchronous/​helpers.py	Uses built-in next and iter.
pymongo/​cursor_shared.py	Imports Self directly from typing.
pymongo/​network_layer.py	Uses asyncio.create_task directly.
pymongo/​periodic_executor.py	Uses asyncio.create_task directly.
pymongo/​pool_options.py	Uses strict zip unconditionally.
pymongo/​pool_shared.py	Removes the TLS injection version gate.
test/​helpers.py	Updates generated task creation.
test/​asynchronous/​helpers.py	Updates asynchronous task creation.
test/​test_client.py	Removes obsolete context-manager gating.
test/​asynchronous/​test_client.py	Removes obsolete async context-manager gating.
test/​test_discovery_and_monitoring.py	Removes the obsolete barrier skip.
test/​asynchronous/​test_discovery_and_monitoring.py	Removes the obsolete barrier skip.
test/​test_encryption.py	Accepts the modern TLS EOF error unconditionally.
test/​asynchronous/​test_encryption.py	Accepts the modern TLS EOF error unconditionally.
test/​asynchronous/​test_locks.py	Enables Python 3.11 asyncio tests unconditionally.
test/​test_retryable_writes.py	Uses asyncio.create_task directly.
test/​asynchronous/​test_retryable_writes.py	Uses asyncio.create_task directly.
test/​test_ssl.py	Removes obsolete async TLS test gates.
test/​asynchronous/​test_ssl.py	Removes obsolete async TLS test gates.

🧠 Review effort: Balanced

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[sleepyStick]

nit: can this be put onto the same line? or like can we fix the spacing here?

[sleepyStick]

i could be wrong, but i think these type ignores can be removed here? (and on line 101)