Broaden Python version support to 3.9+

[Copilot]

Package currently requires >=3.11, blocking installation for users on Python 3.9.x. Codebase uses no 3.11+ specific features and is compatible with 3.9+.

Changes

• pyproject.toml: Update requires-python from >=3.11 to >=3.9,<3.13
• pyproject.toml: Add Python 3.9 and 3.10 classifiers
• pyproject.toml: Update ruff target-version to py39
• .github/workflows/test.yml: Expand CI matrix to test on Python 3.9, 3.10, 3.11, 3.12

Code already uses from __future__ import annotations for PEP 563 compatibility, making type hints with | syntax and dict[K, V] work on Python 3.9.

Original prompt

Update the repository somebox/runcue (repo ID: 1119183521) so it works with Python 3.11. Currently the project requires Python 3.9, which causes downstream issues.

Goals

• Adjust packaging metadata so the project officially supports Python 3.11.
• Ensure CI and test tooling run on Python 3.11.
• Remove/relax any explicit Python 3.9-only constraints across the repo.
• Keep changes minimal and backward-compatible where reasonable (unless the repo clearly intends to support only 3.11+).

Requirements / Acceptance criteria

1. Identify where Python version is enforced (e.g., pyproject.toml, setup.cfg, setup.py, Pipfile, poetry.lock, requirements*.txt, tox.ini, noxfile.py, pre-commit, GitHub Actions workflows).
2. Update constraints to include Python 3.11.
   • Prefer python_requires = ">=3.9,<3.12" (or equivalent) unless repository policy indicates otherwise.
   • Update classifiers (e.g., Programming Language :: Python :: 3.11).
3. Update CI matrix to test on 3.11 (and keep existing supported versions if applicable).
4. Update any tox/nox/testing environment configs to include py311.
5. Run/adjust tests as needed; fix any compatibility issues discovered (e.g., stdlib changes, dependency compatibility).
6. Update documentation (README, contributing) that states Python 3.9 requirement.

Deliverables

• A pull request with clear title and description summarizing what changed and why.
• All CI checks passing.

Notes

• The user confirmed they want a PR.
• Assume default branch is main unless discovered otherwise during implementation; if it differs, adjust base accordingly.

This pull request was created from Copilot chat.

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