Explicit support and testing against Python 3.13 and 3.14

[asnare]

Changes

This PR updates the project to explicitly support and test against Python 3.13 and 3.14. Further to this, the project tooling has been refreshed somewhat.

Changes include:

• Upgrading Hatch in CI/CD: 1.15.0 → 1.16.5 (earlier versions are broken due to pip changes).
• Hatch now manages the python version instead of using the system-provided python version.
• Mypy and Pylint have been updated, with code changes to satisfy the newer versions.
• Pytest: 8.3 → 9.0 (and the plugins have been updated)
• GitHub actions have also been updated.

We also now run integration tests even if the PR is a draft to help catch problems before marking it for review.

Tests

• existing unit tests
• existing integration tests

[github-actions]

✅ 40/40 passed, 6 skipped, 20m20s total

_{Running from acceptance #239}