Drop support for Python 3.10

[shahar1]

Drop Python 3.10 support from Airflow, Task SDK, airflowctl, providers, shared libraries, the Helm chart tooling and the dev/CI toolchain. The minimum supported Python is now 3.11; the default CI/breeze Python moves from 3.10 to 3.11.

Python 3.10 reaches end of life in October 2026, and an increasing number of our dependencies have already dropped it (see the --no-explain-why workaround in finalize-tests.yml, which this PR removes along with 3.10).

What changes

• requires-python = ">=3.11" and the Programming Language :: Python :: 3.10 classifier removed in every pyproject.toml (core, task-sdk, airflow-ctl, all providers, shared/*, dev/test distributions). uv.lock files regenerated.
• Breeze: ALLOWED_PYTHON_MAJOR_MINOR_VERSIONS / ALL_PYTHON_MAJOR_MINOR_VERSIONS are 3.11–3.14; providers compatibility matrix runs on 3.11; the dead PYTHON_TO_MIN_AIRFLOW_MAPPING constant and its unused is_airflow_version_supported_for_python helper are removed.
• CI/Docker: default Python 3.11 in composite actions, workflows, devcontainer, Dockerfile/Dockerfile.ci and scripts/docker. The PGP branch for verifying the Python source tarball is removed (3.11+ ships Sigstore bundles); the python-3.10.asc key and its entry in update_docker_gpg_keys.py go with it.
• Code: tomli fallbacks replaced by tomllib; typing_extensions imports of Self/Unpack/assert_never replaced by typing; the asyncio.Runner re-implementation in BaseOperator.event_loop() removed; sys.version_info < (3, 11) test skips removed. tomli dropped from build-system.requires and prek hook dependencies.
• Ruff: with the new baseline ruff rewrites timezone.utc to datetime.UTC (UP017) and Unpack[tuple[...]] to *tuple[...] (UP044) across the repo - that is the bulk of the diff. UP042 (str, Enum -> StrEnum) and ASYNC109 become reportable on 3.11 and are added to the ruff ignore list with a rationale: both change runtime behaviour or public signatures and need per-site judgement.
• Inline script metadata (# requires-python) in scripts/ci/prek/*.py and dev/** bumped to 3.11; docs, READMEs, contributing docs and generated files updated (update-tested-versions, update-supported-versions, update-pyproject-toml, generate-pypi-readme, update-breeze-cmd-output, update-inlined-dockerfile-scripts).

Deliberately kept 3.10 references

• .github/actions/prepare_all_ci_images/action.yml still restores a 3.10 (and 3.9) CI image: the action is shared with release branches that still support those versions (see the comment in the file and Update ASF "stash" action to allow list of keys #45268).
• ALL_HISTORICAL_PYTHON_VERSIONS, PYTHON_3_10_TO_3_14 and ALL_PYTHON_VERSION_TO_PATCHLEVEL_VERSION["3.10"] in global_constants.py: used to reason about older Airflow releases (SBOM, compatibility matrix) and to build images for release branches.
• python:3.10-slim-buster in the Kubernetes decorator/pod operator tests and python_version="3.10" in the Vertex AI Ray hook: those are container/Ray runtime versions, not the Airflow interpreter.
• Changelogs and dev/breeze/doc/adr/0002-*.md keep their historical wording.

Checks run

• uv run --project dev/breeze pytest dev/breeze/tests (1160 passed; test_publish_docs_to_s3.py skipped locally due to a botocore/Python 3.14 import issue unrelated to this change).
• uv run --project scripts pytest scripts/tests (1602 passed), uv run --project dev/registry pytest dev/registry/tests (271 passed).
• Targeted task-sdk and shared/logging unit tests for the simplified code paths pass; the provider tests that lost their skipif markers need a DB and were not run locally.
• ruff check / ruff format clean; prek run --from-ref main --to-ref HEAD --stage pre-commit - see the PR checks for the result on CI.

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Was generative AI tooling used to co-author this PR?

• Yes — Claude Code (Fable 5.1)

Generated-by: Claude Code (Fable 5.1) following the guidelines

[shahar1]

Superseded by a stacked set of smaller PRs so each piece can be reviewed on its own (stack #74160):

1. Drop Python 3.10 from CI, Breeze and the container images #74151 Drop Python 3.10 from CI, Breeze and the container images
2. Bump inline script metadata to Python 3.11 #74152 Bump inline script metadata to Python 3.11
3. Remove Python 3.10 compatibility shims #74153 Remove Python 3.10 compatibility shims
4. Apply ruff Python 3.11 fixes to core, Task SDK, shared and airflowctl #74154 Apply ruff Python 3.11 fixes to core, Task SDK, shared and airflowctl
5. Apply ruff Python 3.11 fixes to providers #74155 Apply ruff Python 3.11 fixes to providers
6. Apply ruff Python 3.11 fixes to dev tooling, scripts and test suites #74156 Apply ruff Python 3.11 fixes to dev tooling, scripts and test suites
7. Require Python 3.11 in all distributions #74157 Require Python 3.11 in all distributions
8. Update provider READMEs for the Python 3.11 baseline #74158 Update provider READMEs for the Python 3.11 baseline
9. Update docs for the Python 3.11 baseline #74159 Update docs for the Python 3.11 baseline

The combined diff of the stack is identical to this PR (plus the newsfragment rename). Closing in favour of the stack.

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Drafted-by: Claude Code (Fable 5.1) (no human review before posting)