Pyheadtail

**Changes:**
* Corrected the sign of `wake_strength` in `function_longitudinal` to ensure a positive wake corresponds to energy loss (consistently with what is already done in the longitudinal resonator).
* Correct the `interp1d` interpolation function by adding `bounds_error=False` and `fill_value=0` as done for the transverse wakes.

**Changes:**
- Adapt to scipy >=1.14

**Full Changelog**: https://github.com/PyCOMPLETE/PyHEADTAIL/compare/v1.16.2...v1.16.3

**Changes**
- Compatibility with cython 3.0

**Full Changelog**: https://github.com/PyCOMPLETE/PyHEADTAIL/compare/v1.16.0...v1.16.1

- Optimization of wake tables giving significant speed-up
- Add a new set of simulation examples and simulation-based tests with numerical checks
- Remove unused modules and remaining deprecated syntax after Python 3 migration

- Add LongSpaceChargeRectPipe class
- Change release and versioning method
- Several improvements in GPU support
- General package cleanup

**Fixes:**
- Small changes in the documentation.

**This version is incompatible with Python 2!**