Update supported Python versions to 3.10–3.13, set 3.12 as primary

[Copilot]

• Update pyproject.toml: requires-python → >=3.10, ruff target-version → py312, added Python version classifiers
• Update noxfile.py: python_versions → ["3.12", "3.10", "3.11", "3.13"] (3.12 as main/first)
• Update .github/workflows/tests.yml: CI matrix (removed 3.9, added 3.13, 3.12 as main), coverage job Python 3.14 → 3.12
• Update .github/workflows/release.yml: Python version 3.14 → 3.12
• Update .github/workflows/benchmark.yaml: Python version 3.14 → 3.12
• Update .pre-commit-config.yaml: --py37-plus → --py310-plus
• Update .readthedocs.yml: Python 3.10 → 3.12
• Update README.md: Python requirement text updated
• Update CONTRIBUTING.md: Python requirement text updated
• Update ADR doc: Python version references updated
• Fix pre-commit issues: ruff import ordering and pyupgrade Python 3.10+ syntax in config.py and metrics.py

Original prompt

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This section details on the original issue you should resolve

<issue_title>update python versions</issue_title>
<issue_description>Support only Python 3.10, 3.11, 3.12, 3.13. make 3.12 the "main" version

change all configuration files, all github workflows, all pre-commit, pyproject.toml and other places where python version may exist in the project</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes update python versions #921

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[tomwillis608]

@copilot please resolve build issues:

pre-commit run --all-files
git add .
git commit -m "Fix pre-commit issues"

[Copilot]

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[tomwillis608]

@copilot
https://gh.io/copilot-coding-agent-docs please resolve build issues:

pre-commit run --all-files
git add .
git commit -m "Fix pre-commit issues"

[Copilot]

@copilot
https://gh.io/copilot-coding-agent-docs please resolve build issues:

...

Fixed in commits 2bf02f5 and 98e80cd. Running pre-commit run --all-files revealed two auto-fixable issues triggered by the --py310-plus pyupgrade upgrade:

• config.py: ruff fixed stdlib import ordering (zoneinfo moved before third-party toml)
• metrics.py: pyupgrade upgraded Optional[datetime] → datetime | None and moved Iterable from typing to collections.abc; ruff then corrected the resulting import ordering

All pre-commit hooks now pass cleanly.