[py] Support Python 3.14 and drop Python 3.9

[cgoldberg]

User description

💥 What does this PR do?

• Adds support for Python 3.14 (released: 10/7/2025): https://docs.python.org/3/whatsnew/3.14.html

• Drops support for Python 3.9. This version is officially EOL as of 10/31/2025. Some of our dependencies have already dropped support for 3.9 and it is becoming problematic to continue supporting it.

• Changes the default version of Python we use in CI workflow jobs to 3.10

• Updates all Python dependencies for testing and packaging.

• Updates Bazel and workflow configurations to enable running unit tests on the oldest/newest versions on Python we support.

• Removes build requirement from CI jobs that don't require it

🔄 Types of changes

• Build/Packaging/Testing

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PR Type

Enhancement

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Description

• Add Python 3.14 support and drop Python 3.9

• Update CI default Python version to 3.10

• Upgrade dependencies and build tools

• Update documentation and installation instructions

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Diagram Walkthrough

flowchart LR
  A["Python 3.9"] -- "drop support" --> B["Python 3.10-3.14"]
  B -- "update" --> C["CI workflows"]
  B -- "upgrade" --> D["dependencies"]
  C --> E["documentation"]
  D --> E

Loading

File Walkthrough

	Relevant files
Configuration changes	5 files ci-python.yml Update CI Python version to 3.10                                                  +6/-6      update-documentation.yml Update documentation workflow Python version                          +2/-2      MODULE.bazel Update Python toolchain and dependencies                                  +4/-4      BUILD.bazel Update Python classifiers and requirements                              +5/-5      pyproject.toml Update Python requirements and dependencies                            +5/-5
Dependencies	5 files multitool.lock.json Update ruff version to 0.13.3                                                        +10/-10  requirements.txt Upgrade Sphinx to 8.1.3                                                                    +1/-1      requirements.txt Update development dependencies                                                    +7/-7      requirements_lock.txt Regenerate locked requirements for Python 3.10                      +106/-85 tox.ini Update mypy and ruff versions                                                        +2/-2
Documentation	1 files index.rst Update supported Python version documentation                        +3/-3

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[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Build Matrix Consistency Ensure CI/build configurations (Bazel toolchains, pip parse hub, and any test matrix) consistently include Python 3.14 and that the referenced rules_python version actually supports 3.14 to avoid resolution or toolchain selection failures. python.toolchain(python_version = "3.14") use_repo(python, "pythons_hub") pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip") [ pip.parse( hub_name = "py_dev_requirements", python_version = version, requirements_lock = "//py:requirements_lock.txt", ) for version in [ "3.9", "3.10", "3.11", "3.12", "3.13", "3.14", ] ] Version Constraint Change Relaxing requires-python to ">=3.9" broadens supported versions; verify this aligns with policy and that packaging/CI wheels and metadata remain correct for all versions, including future 3.x, to avoid unintended installs. requires-python = ">=3.9" classifiers = [ "Development Status :: 5 - Production/Stable", "Intended Audience :: Developers", "Operating System :: POSIX", "Operating System :: Microsoft :: Windows", "Operating System :: MacOS :: MacOS X", "Topic :: Software Development :: Testing", "Topic :: Software Development :: Libraries", "Programming Language :: Python", "Programming Language :: Python :: 3.9", "Programming Language :: Python :: 3.10", "Programming Language :: Python :: 3.11", "Programming Language :: Python :: 3.12", "Programming Language :: Python :: 3.13", "Programming Language :: Python :: 3.14", ]

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Restrict Python version to avoid issues Add an upper bound to the requires-python specifier to prevent future compatibility issues, changing it from ">=3.9" to ">=3.9, <4.0". py/pyproject.toml [12] -requires-python = ">=3.9" +requires-python = ">=3.9, <4.0" Apply / Chat Suggestion importance[1-10]: 6 __ Why: The suggestion correctly identifies that requires-python = ">=3.9" is too permissive and could cause future installation issues with Python 4.0, proposing a safer upper bound which is a packaging best practice.	Low
Update

[cgoldberg]

@shbenzer @navin772 Do you see any issues with dropping support for Python 3.9?

[navin772]

No issues if the CI passes with 3.10, which it does, there seems to be a minor issue with docs and mypy CI, it is looking for python 3.1 instead of 3.10.

[shbenzer]

I agree w/ @navin772, as long as we can fully support the next up I'd like to keep us from supporting anything not supported by the Python project. To answer your question directly though, I am not aware of any issues w/ dropping 3.9 specifically.

[cgoldberg]

it is looking for python 3.1 instead of 3.10.

Fixed.

I'll merge this in a few days after 3.14 is officially released.

[navin772]

LGTM!