Context

python-bsonjs currently supports Python 3.9+ and ships a stable-ABI wheel pinned to Py_LIMITED_API 0x03090000 (cp39). Python 3.10 reaches end-of-life on 2026-10-31. Once that happens, python-bsonjs should drop support for it, following the project's practice of dropping a version once it goes EOL (e.g. 3.8 was dropped in 0.6.0).

Definition of done

* requires-python in pyproject.toml raised from >=3.9 to >=3.11, and the Programming Language :: Python :: 3.9 / 3.10 classifiers removed.
* Py_LIMITED_API in setup.py bumped from 0x03090000 to 0x030B0000, and the bdist_wheel py_limited_api option bumped from cp39 to cp311.
* CI workflows updated to stop testing 3.9/3.10, if still present in the matrix.
* CHANGELOG.rst entry noting the dropped versions.

Pitfalls

* Don't land this before 2026-10-31 — Python 3.10 is still supported until then.
* Bumping the limited-API target changes the published wheel's ABI tag (cp39-abi3 → cp311-abi3), which is a breaking change for anyone pinning to the old tag.