Automatically install windows-curses on Windows #18

Tiny8 uses the curses, which does not work on Windows by default.

Add windows-curses as a conditional dependency in pyproject.toml:

[project]
dependencies = [
    "numpy",
    "windows-curses ; sys_platform == 'win32'"
]

This should allow Windows users to run tiny8 without extra steps, while keeping Linux/macOS unchanged.