Ndsplines

- Boundary conditions may now be passed to `make_interp_spline`
- Wheels for Python 3.12 and 3.13 now available
- Support for numpy 2
- Dropped support for Python 3.7

What's Changed

Maintenance and cleanup, plus Python 3.11 wheels.

Most notably, the somewhat complicated logic with whether NumPy and/or Cython are pre-installed has been removed in favor of relying on build dependencies (PEP 518) and an environment variable to opt out of compiling (see README).

**Full Changelog**: https://github.com/kb-press/ndsplines/compare/v0.1.4...v0.1.5

What's Changed

* Use oldest-supported-numpy by ixjlyons in https://github.com/kb-press/ndsplines/pull/72
* Fix deprecation warnings from numpy for builtin types by ixjlyons in https://github.com/kb-press/ndsplines/pull/71
* Rework actions workflows by ixjlyons in https://github.com/kb-press/ndsplines/pull/73

What's Changed

* Raise exception for invalid implementation name by ixjlyons in https://github.com/kb-press/ndsplines/pull/66
* Remove package-level impl attr and add a getter by ixjlyons in https://github.com/kb-press/ndsplines/pull/68
* Switch to GitHub Actions by ixjlyons in https://github.com/kb-press/ndsplines/pull/69