Switch some files to use future annotations, follow ruff guidance to …

[flavour]

Better to look forward than back & hence use modern-style Type Hints.

Easier for new contributors if Ruff errors fixed rather than appearing when not due to their changes.

Changes

Added pyupgrade pre-commit hook to help migrate the old-style type-hints.

How I tested this

Relying on Unit Tests currently

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.