Update GitHub Actions and Python versions to latest standards

[Copilot]

Updates CI workflow to use current GitHub Actions versions and modern Python releases.

Changes

• GitHub Actions: actions/checkout@v3 → v4, actions/setup-python@v4 → v5
• Python matrix: ["3.9", "3.10"] → ["3.10", "3.11", "3.12"] (drops EOL 3.9, adds current releases)
• LICENSE: Updated copyright year range to 2022-2026

Original prompt

update this respository to the latest standard

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