simplefractions 1.4.0

This is a minor release that updates packaging infrastructure, drops support for Python
versions older than Python 3.10, and modernises some of the core code. The core logic
and functionality is essentially unchanged.

Changes

• Update the release workflow to use uv. (#44)
• Rename an internal helper function to silence linter complaints about importing
  a private function. (#43)
• Rework the logic that finds the interval rounding to a float to use math.nextafter
  instead of using struct. (#42)
• Modernise type hints, replacing uses of typing.Optional, typing.Union,
  typing.List and typing.Tuple with more modern syntax. (#41)
• Modernise packaging to use uv, and add a developer guide in DEVELOP.md. (#40)