Cxroots

- Changes derivative approximation to use 1D five-point sencil
- Pin scipy<1.15 due to upcoming `scipy.integrate.romberg` removal
- Change project to use pyproject.toml
- Set __version__ using setuptools-scm

- Adds compatibility with numpy v2 by replacing deprecated types (thanks [MartinCapraro](https://github.com/MartinCapraro))

- Temporarily require numpy<2

- Requires Python >= 3.10
- Removed `df_approx_order` parameter
- Removed `cx_derivative` function
- Removed `find_multiplicity` function
- Removed dependency on numdifftools
- Removed upper bound on required numpy version
- Removed `util.integrate_quad_complex` and use `scipy.integrate.quad`'s `complex_func` argument instead
- Renamed `NumberOfRootsChanged` to `NumberOfRootsChangedError`
- Switch to [ruff](https://github.com/astral-sh/ruff) formatting/linting

- Improved reliability by subdividing contours that produce invalid approximations for multiplicites, rather than ignoring the individual invalid approximations.

- Record in setup.py that only numpy < 1.25 will work with cxroots currently (https://github.com/rparini/cxroots/issues/285)
- Fix type annotation for `util.integrate_quad_complex` function
- Add more debug logging for root counting
- Adjust root counting error advice to include chaning integration method
- Fix type issue in contour.__call__ by hard coding array dtype